Covid Vaccines – a few more links

As more coronavirus vaccine manufacturers have press releases touting their vaccine trial news, we all need good sources to understand what is going on. Therefore, here are a few more links to help you understand all of the information being thrown at you:

  1. My first blog post about the covid vaccines
  2. Deplatform Disease: a great website by biochemist Edward Nirenberg, primarily discussing vaccines and Covid-19.
  3. Skeptical Raptor’s blog debunking common vaccine myths, but also putting in a nice amount of skepticism
  4. Some recent news articles that may be of interest

November 2020: Covid Vaccine News

Guest post by vaccine advocate Denise Kesler Olson. She currently works for an Immunization Coalition in Arizona, helping others feel as passionate about vaccines as she does. You can read how she got involved in the immunization movement here.  This information originally appeared on her Facebook wall, and she has graciously allowed me to post this edited version on my blog. – Dr. Shaham

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Part I: “But How Do We Know If It’s Safe!?”

The most common criticism I get is that I keep telling you how every vaccine is safe, and therefore I must unconditionally love all vaccines and accept them all blindly. No. I – and really, we’re talking about the scientific establishment I support and not me personally –accept only vaccines that have been through the rigorous testing process and are found to be safe and effective. The vaccines on our standard schedule have cleared that hurdle. Covid vaccines aren’t in that category yet. We do not know if they work nor if they are safe. I wouldn’t recommend everyone get them yet, and no responsible organization should either.

A little background information will go a long way to help us here. Vaccines are a special type of medical product because they are given to healthy people instead of sick people. This might seem like a small thing, but it’s actually a HUGE difference. Pharmaceuticals are only ethically given when the possible benefit outweighs the possible risk. If you are already sick, it may be worth risking side effects, especially when they rarely happen or if they are less serious than the problems you already have. A vaccine given to healthy people must never make them into really sick people, or the whole point of preventing illness is defeated! Any effects need to be better than the alternative of not getting the vaccine at all. 

Vaccines need to pass through four specific development phases to be proven safe and effective (preventing the disease). If any serious side effects are found throughout this process, the vaccine will not be approved for mass use – about 60% of vaccines fail to be approved in the end (compare this to 84% of other pharmaceuticals which fail). First, various vaccines that have worked in the laboratory setting, and look good on paper and computer modeling, are tested on animals to prove that the formulation isn’t harmful to live beings and see which candidates are the most promising. The vaccines that work safely and as expected in animals can then move forward to be tested in humans in phase I, II, and III clinical trials. Pediatric vaccines (the ones we use in kids) usually undergo phase IV clinical trials as well, which are formal studies that occur after the FDA approves a vaccine. Check out this infographic from the CDC about how a vaccine gets to market (click on the sentence to open the link in a new window) or click here for a short YouTube video about the process

There are currently Covid vaccines undergoing phase I, II, and III trials in adults all over the world. The phase III studies on people are double-blind. That means the participants are divided into groups, and half of the people are randomized to receive the real vaccine that is being tested, and half receive something else (a placebo), such as a saltwater injection or a different vaccine. Neither the patient nor the medical staff administering the vaccine knows if the real vaccine was given. Only the data analysts have this information, and it is kept separately from any information identifying people in the trials, such as their name, birthday, street address, or characteristics. This is important because not everything that happens to people after getting a shot will be because of the injection. People in both groups will get sick or injured by random chance -especially when following up with them for a long time. Scientists look for patterns. If one thing shows up repeatedly in the group of people who got vaccinated, then that may be a sign that the vaccine caused it.

This knowledge will help you understand scary headlines in the news. Recently, there were wide reports that someone in Brazil had died while participating in a vaccine trial. When the researchers paused the trial, they used emergency protocols to unblind his records.  It turned out that he was not given the real vaccine during the trial, so the vaccine they were testing could not be the cause of his death.

Obviously, you test vaccines not just to prove that they are safe but also to prove that they prevent people from getting sick. There are two ways that people can go about this. One way is to continue watching phase III trials (around 30,000 people or as many as they can get for vaccine trials) for a very long time until enough people are naturally exposed to the virus. Over time, you hope to see a pattern of people who were given the real vaccine not getting sick, hardly ever getting sick, or only getting mildly sick. If the vaccine does not work, then the people who got the real vaccine and the people who got the placebo will get sick roughly in the same amount and severity overall. Remember this when you hear numbers like “this vaccine is only 50% effective,” because it means people in the vaccinated group were half as likely to get ill with COVID-19 compared to the placebo group. While that would not be the best, it would be a huge reduction of disease overall.

The other way to see if vaccines work is controversial, but it did get approval for use in the UK recently in healthy and willing volunteers. This is the old-fashioned challenge trial. In a challenge trial, you give the vaccine and then deliberately try to infect those people with the disease you are trying to prevent. The advantage is knowing right away if people get sick in the same numbers and skipping months of waiting around for people to become exposed. Still, infecting people on purpose with a disease, when you do not know if you have a safe or effective vaccine, has many disadvantages and is considered unethical by many people. 

Part II: Operation Warp Speed

There are a couple of hurdles that keep vaccines from coming to the market quickly, even if the idea is good and it works. 1: There may not be enough money to continue research and development. In that case, work must be paused as researchers try to obtain new grants/investors/sources of funding. 2: It’s hard to scale up the production of an effective vaccine so that there are enough doses to immunize everyone in a large population. It costs quite a bit of money to build or retrofit a factory and obtain all of the necessary materials to make millions of doses of a new vaccine.

Operation Warp Speed was passed as part of the CARES act in March 2020 to speed up a successful Covid vaccine’s availability. Ten billion dollars went into funding a public-private partnership that gives R&D money to companies with candidate vaccines, as well as supplying funding to scale up factories to manufacture those vaccine candidates, even when we are not sure they will ever be approved. They did this with the knowledge that some of them would probably not be proven to be effective in the trials and would ultimately have to be tossed out, but that if one worked, then there would be millions of doses sitting ready to be shipped out as soon as final approval was given. The reasoning behind this effort was set out by top economists who supposed that a delay of even one year could cause much more economic damage and turmoil than simply funding the vaccines upfront and getting things back to normal.

Like everything that comes out of Congress, the law is very complicated and full of fine print. It leaves a lot of questions, such as:

  • What loopholes could pharma companies exploit to inflate their stock prices?
  • Should the American people have to pay for a vaccine funded by taxpayer dollars?
  • Should we be awarding money to foreign companies under this program?
  • Were contracts awarded fairly and subject to enough scrutiny?

And on and on and on. We will probably be talking about what went right and what went wrong with Operation Warp Speed for decades to come. However, that is an argument for somewhere else. I brought it up because I want to help everyone understand that Operation Warp Speed does not fundamentally change the clinical trial process I talked about before, where we check the safety and efficacy of vaccines. It has a dramatic name, but it should really be called “Operation Fund COVID Vaccines.” There are legitimate reasons to critique the operation, but they have nothing to do with the safety and effectiveness of the eventual vaccines produced. Questions about pharmaceutical companies, including how much money they should be allowed to make if they receive public funds, are economic and political questions at heart. The companies participating still have to prove that their vaccines are safe and work; otherwise, their whole tax-payer funded factory will just sit there gathering dust.

Addendum from Dr. Shaham: Operation Warp Speed is allowing manufacturers to reduce the typical 2-year long phase II clinical trials and 2-year long phase III clinical trials into an overlapping 6 month trial period before assessing the vaccine safety and efficacy, due to the urgency of getting a vaccine out to halt the pandemic, and a large number of people in the trials. However, this does shorten the time we have to determine the long term side effects of the vaccine. For Covid-19 we also do not know the long term effects of the virus itself, since it is new to humans (but has been in animals for years); therefore, there will be ongoing data collection and research long after initial approval of a covid vaccine, and we will be learning about both what the virus itself does, and the vaccine does, for years to come. 

Part III: Big News in Big Pharma: Pfizer says their vaccine is 90% effective. 

Two large but competing pharmaceutical companies, Pfizer (of Germany) and Moderna (of the U.S.A.), are attempting to make their covid vaccine candidates a new way. Not only are these two vaccine candidates designed to fight a new infection, Sars-CoV-2, but they are designed using mRNA (messenger RNA).

A typical vaccine takes a virus (or bacterial) toxin, or parts of the microbe that were grown in a lab, harvests it, kills it, chops it up, and purifies it until only 1 part is left, which we call the antigen. The antigen is mixed with things that help your body recognize it and defend itself against it, and that vaccine is injected either under your skin or into a muscle. Your body then mounts an immune response under the belief that these inert germs pose a real threat. Later, when the body actually encounters the real germ, it is easy for your immune system to retrieve the antibodies created in response to the vaccine, copy them, and use them to prevent or blunt the real thing’s effects.

The mRNA vaccines work by skipping the part where the lab makes an antigen. They are counting on the fact that our own body is as good as any lab at manufacturing parts of a virus. After all, that is the reason that viruses want to infect you in the first place. They can’t duplicate themselves the way bacteria can, so they trick your cells into making more viruses by hijacking their ability to make proteins. First experimented with for cancer treatment, the idea of the mRNA vaccine is to trick a few of your cells into manufacturing parts of the virus – NOT the whole virus, so it can’t give you Covid. It tells some of your cells to make the Sars-CoV-2 spike protein, for example, which is enough to make your body mount an immune response against the real virus.

Does this actually work? We don’t know yet, but in a press release on November 9, 2020, Pfizer claimed that it is working well in their data so far. Remember, in trials, half of the people receive the real vaccine they are testing, and half of them receive something else. Then everyone has to wait around and monitor the participants until people get exposed to Sars-CoV-2. They have regular visits with researchers, have blood and nasopharyngeal swabs examined, keep symptom journals, and report everything. Pfizer claims that out of the more than 44,000 people in their trial, only 94 people so far have been sick with Covid-19. When the researchers analyzed the data, they found that only nine of the people with Covid got the real vaccine candidate. The other 85 people were in the control group. That certainly looks like a pattern starting to develop. A group of different researchers ran a statistical analysis and found that if this rate continues, the vaccine would be >90% effective. This is well above the 50% floor the FDA set for approval of any COVID vaccine, moving it from being as efficacious as the influenza vaccine to put it more in line with the far more effective polio vaccine. For more information on the statistical side, check out the tweet threads linked here

So what are the catches? The most important is this trial is not finished, and this data came from a press release, not a journal. Only once is published can independent researchers run more analyses to validate the claims. There also haven’t been enough Covid-19 cases in the participants to know if this pattern will hold, and the FDA has said that they would not even consider an emergency application for use until there had been at least 161 confirmed cases of Covid-19 in the trial. We don’t yet know if the vaccine prevents severe disease because it was reported that no one so far has gotten seriously ill. Since this was a press release, they did not address the biases in their research, such as volunteers for the vaccine trial being more likely to wear masks and socially distance, nor confounding factors, like the participants’ socioeconomic status. Another consideration for this new vaccine type is that it must be kept very cold at -80 degrees C, and once the vaccine is thawed, it must be used very quickly. It won’t be easy to distribute it outside of a large hospital setting since it has unique storage requirements.

Another potential effect for people to be aware of and that is vaccines of this type by their very nature stimulates both the nonspecific and specific set of immune responses our body has. Your body may try to fight this “infection” with a fever and make you feel achy and tired for a few days before it gets down to building specific antibodies. That wouldn’t be dangerous, but it would be something to be aware of, or you may be afraid you’d gotten ill from the vaccine. The side effects are likely to be a bit worse than those from the annual flu shots.

In the end, it is hard to know if this is the vaccine that turns out to be the most widely used. Assuming the trend holds; however, I think it could be a useful measure to vaccinate healthcare workers who are most at risk.

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A final thought added by Dr. Shaham:

The data is promising, but we have to have patience and wait for more data and independent analysis before making any decisions about using this (or any other) vaccine in the population at large. The mRNA vaccines will need even more long term data before their safety can be established since they are a totally new type of vaccine. My best prediction at this time is that more data will be available in early 2021 so that people at very high risk (like high-risk healthcare workers) will start to get one of the covid vaccines by Spring 2021. Still, it will be a long time before something is tested enough and available to children.

Vaccine Science Made Simple

This is a guest post by Kimberly Mulligan, PhD from the department of biological sciences at California State University Sacramento

Hi parents! Scientist here. I decided to write a long post about vaccines to help shed some light on how vaccines work and, hopefully, bring some clarity to topics of debate. The amount of misinformation about vaccines feels a little out of control to me. And no matter what you think about vaccines, it’s tough to wade through this information without a scientific background. FYI, my science background: PhD in developmental biology from Stanford University, postdoctoral research at UCSF on the molecular basis of brain development with an emphasis on a group of genes implicated in autism and other neuropsychiatric disorders, and I just joined the faculty at CSUS this January where I teach molecular cell biology and will have a research program focused on the molecular basis of neurodevelopment and neuropsychiatric illness. Ok, on to the fun stuff.  (It’s long because I wanted to be comprehensive and address all of the questions I usually get about vaccines.)

First, I ask that you read this with an open mind.  Having an open mind is an integral quality of good scientists – it is the only way to objectively analyze data. (Open minds are wise minds!) I also want to add that this debate gets nasty, but in the end we all love our kids and want what’s best for them (as a mama of two, I get that).  I am not judging, I do not feel that is my place as a scientist – my place as a scientist is to arm you with information and help you better understand that information.

Important vocabulary: pathogen = disease-causing bacteria or virus

Q: Ok, so what are vaccines? (I feel like this very basic question is often not clearly answered.) 

A: Usually they are viruses or bacteria that have been modified so they cannot hurt you, but still look like pathogens to your immune system. That part is key. When a weakened pathogen (or “acelluar” pieces of a pathogen) enters your body your immune system responds by making antibodies that will bind specifically to that pathogen, and target it for destruction. Here’s the really cool part – our immune system makes cells called memory B cells that will stay in our body for a really long time (depending on how strong the vaccine is). These memory B cells are primed to make antibodies specific for that pathogen if you were to get infected again. This is important because our immune response can take a long time – long enough for pathogens to have debilitating and sometimes lethal consequences. If you have those B cells ready to go, your body makes specific antibodies that will get rid of the pathogen before it hurts you.

Q: What about the other scary sounding stuff in vaccines?

A: They are all there to make sure the vaccine stays safe and effective. And while they sound awful, they are all actually totally safe in the amounts present. For example, formaldehyde sounds scary, but did you know that it is a normal metabolic byproduct that your body produces in small amounts constantly? You produce more formaldehyde over a matter of minutes than you get from a vaccine. Another fun fact: there is 4-15 times more formaldehyde in a single apple than any one vaccine. And your body simply processes it and gets rid of it (again, it knows how since you are always producing it). Aluminum?  Present in things ranging from organic pears to natural breast milk. One of the first things biochemistry students learn is that dose matters. Yes, large amounts of aluminum and formaldehyde are bad…but large amounts of water can be lethal. Oh, and mercury-containing thimerosol is no longer in early childhood vaccines because it was removed due to public outcry. However, there is still zero scientific data to suggest that thimerosol has any detrimental effects. In fact, the type of mercury in thimerosol is ethyl mercury, which is readily flushed from the body. The bad mercury that our body has a harder time getting rid of is methyl mercury (found in tuna).

Q: Why should you trust a big pharma who profits from vaccines? 

A: My first answer is that you don’t have to. There are a lot of scientists who have published research on the safety of vaccines that are not affiliated with big pharma and do not profit from the results of their findings. They are people like me – who became scientists because they wanted to help learn more about biology in order to diminish human suffering. We work for academic institutions, not big pharma. We ask questions without a vested interest in the answers. These are the scientists that can provide you with unbiased information. You can do a search for yourself on the largest database of scientific journals here: http://www.ncbi.nlm.nih.gov/pubmed

You will find that when you search for studies on autism and vaccines, of the hundreds of studies conducted, there is still no scientific data to suggest a link between the two. For example, every epidemiological study conducted on populations of children living in the same community has shown autism occurs at the same rate in vaccinated and unvaccinated children.

  1. What is currently thought to be the cause of autism?

A: It is currently thought that autism is a neurodevelopmental disorder that often begins in utero. A number of the autism risk genes identified affect how the brain develops during gestation. There were actually a couple of papers very recently published indicating specific mutations in a large number of candidate risk genes for autism1, 2. There has also been research showing the influence of environmental factors like maternal antibodies that are present in the womb, which were identified by scientists at the UC Davis MIND Institute3. Autism is a very complicated disorder, and we certainly don’t have all of the answers! But, again, there has been an overwhelming amount of time and money dedicated to investigating a potential link between autism and vaccines, and every study has come back with the same results: there is no data to suggest a link between autism and vaccines.

Q: Back to the big-pharma-makes-a-lot-of-money-argument.

A: Yes, they do. They make money on every drug they produce. I have opinions on big pharma’s business practices that I won’t go into now because it actually has nothing to do with the argument about vaccine effectiveness or safety. For better or for worse, our entire medical system is profit based (our entire economy is, actually). The people at the forefront of the anti-vaccination movement also make a lot of money. That is not why I don’t believe them, though. I don’t believe anti-vaccination proponents because of the absence of scientific data to support their claims. As a scientist, I only believe what the scientific data supports. I read research, not opinions. (That is not meant as a slight to anyone!  I am simply stating my practices. I know that reading primary research papers can be like reading a different language if you do not have a science background, so I would not really expect any non-scientist to have this practice. It’s the same reason I don’t read economics papers. Bleh!)

Q: What about vaccine-related injury?

A: The overall risk is something like 0.003%. And the VAST majority of those 0.003% have minor allergic reactions. Severe allergic reactions can occur, though they are extremely rare. There have been a few cases of autoimmune disorders being triggered by a vaccine. It is not entirely clear whether the vaccine was actually the trigger because it could have been triggered by any pathogen. Importantly, people who are immunocompromised, meaning they have a weakened immune system (chemotherapy patients, HIV patients, genetic immune deficiencies, etc.), cannot be immunized because their immune systems are so weak that even the weakened virus might hurt them. All of these people fall into the class of people who should not get vaccinated and for whom herd immunity is so important!

Q: What is herd immunity?

A: It’s kind of basic math. Viruses cannot replicate on their own. They need to infect a host cell in order to replicate. If they don’t make it into a host cell, they will eventually die. Here’s an easy example: a person infected with a virus walks into a room where there are 20 vaccinated people separating him from a single unvaccinated person. That virus cannot move from the infected person and replicate in any of the vaccinated people because once it gets into their bodies, those memory B cells start pumping out antibodies that kill it before it can replicate and spread. Therefore, those 20 vaccinated people make it harder for the virus to make it to the single unvaccinated person. If half of the people were unvaccinated, that virus would get to have a replication party in all of their cells and would have a much easier time surviving, multiplying, and spreading. Herd immunity is just a basic principle about how infectious pathogens spread. If someone tells you it doesn’t exist, you should be wary of any other scientific information they give you because it means that they have never taken or studied immunology or microbiology and are not qualified to have an educated discussion about those topics.

The tricky thing about vaccines and herd immunity is that herd immunity really only works when a high percentage of the population are vaccinated. If not, then viruses have an easier time spreading around our communities, putting at risk our neighbors who cannot be vaccinated (newborns, cancer patients, etc.), and who are also much more likely to die as a result of infection. That is why the scientific community is so scared.  We feel that even a single death from a vaccine-preventable disease is a tragedy.

Q: Isn’t natural immunity better than vaccine-induced immunity?

A: Well, the immune response is stronger because the pathogens are not weakened, so if you make it through the illness you will, in theory, have a great supply of those memory B cells. The problem is that a lot of these vaccine-preventable pathogens can cause blindness, deafness, brain damage, paralysis, or death. I know of a mama who has a sister who contracted rubella while she was pregnant. Her baby was born blind and deaf because of the infection. So, yes, she now has great immunity to rubella. But she would give anything to have had vaccine-induced immunity prior to her pregnancy.

Q: Why do some vaccines not give lasting immunity? 

A: Each vaccine has a varying degree of effectiveness. By effectiveness I specifically mean the quantity and quality of memory cells that will stick around in the immune system post-vaccine. For example, the smallpox vaccine gave immunity for 65 years whereas the pertussis vaccine only lasts for about 10 years. This is the purpose of boosters. Boosters essentially tell your immune system that it is still important to mount a defense against the pathogen, and replenishes your stock of memory cells.

Q: I heard a lot of adults are to blame for the current measles outbreak. Should adults get vaccinated, too?

  1. Absolutely! If you are unsure of your immunity, you can talk to your medical provider about checking your titer (a measure of your immunity), or you can just get a booster. Even if you’ve had a booster, but can’t exactly remember when and your provider doesn’t do the titer test, getting another booster cannot hurt you.

Q: Why do babies often get fevers after being vaccinated?

A: Part of the natural immune response is the release of molecules called chemokines, which cause fever. As a mama, I know how scary it can be when your little one has a fever, but a post-vaccine fever is indicative of a robust immune response and means they are making great memory B cells. That does not mean you shouldn’t treat your baby’s fever!  (Please consult your pediatrician on when you should treat your baby’s fever.)

Q: What’s up with vaccine shedding?

A: Vaccine shedding is something only possible with a live attenuated virus. This is different from the pertussis vaccine, for example, which is an acellular vaccine, meaning it contains various pieces of the pertussis bacterial molecules and is not infectious at all, cannot cause illness ever, and cannot shed. Again, a live attenuated virus is a weakened virus that reproduces so slowly that a normal immune system will take care of it before it causes any harm. If a person is immunocompromised, live attenuated vaccines cannot be used because their immune system might not be able to handle even a weakened virus. The nasal spray flu vaccine does have a risk of vaccine shedding because the vaccine is administered directly to the mucus membranes of the nose. Therefore, if that recently immunized person were to sneeze onto an immunocompromised person, there is a theoretical possibility that the attenuated virus could give that immunocompromised individual the flu. This is why it is recommended to stay away from immunocompromised individuals for a week after getting the nasal spray flu vaccine.  Other live attenuated viruses are injected into muscle. Some of the weakened virus will get into the lymphatic system, which is where all that good immunity will happen (production of specific antibodies, effector cells, and memory cells that will stay around for a long time). From there, some of the vaccine can enter saliva and mucus, although it is going to be a much lower amount. I think this is why the CDC only has the recommendation to steer clear of immunocompromised individuals in the case of the nasal spray flu vaccine. BUT, and this is critical, the virus that would potentially be shed post-vaccine is the attenuated (weakened) virus that does not cause illness in a person with a normal immune system. This is why vaccine shedding does not cause disease EVER in a person with a normal immune system. It would essentially be like getting an ultra-tiny dose of a vaccine (not enough to even cause an appreciable immune response that would lead to acquired immunity). This is anecdotal, but when my daughter was newborn, my husband did not realize this about the nasal spray flu vaccine when he took our 2 year-old to the doctor…and he got him the nasal spray form of the flu vaccine. I’m happy to report that my newborn daughter did not get the flu. I actually wasn’t really worried; it’s a very minimal risk….but when a person is severely immunocompromised it is important to worry about any potential risk.

Q: If I have a baby that is too young for MMR, could a booster given to a breastfeeding mama give the baby passive immunity through antibodies present in the breast milk?

A: Passive immunity is the transfer of active antibodies from one person to another. This happens during pregnancy when antibodies present in mama cross the placenta to the developing fetus. I recently spoke to an immunologist friend about passive immunity through breast milk. I myself was considering getting the MMR booster to help my 7 month-old baby girl, but he said (sadly) it probably would not boost her passive immunity an appreciable amount (for a virus as strong as measles, anyway). There are five classes of antibodies (IgA, IgG, IgD, IgE, and IgM). The type that is most effective in preventing infection from something like the measles is IgG. These antibodies cross the placenta during pregnancy and give passive immunity to the baby when it is newborn. The primary type of antibody that gets into breast milk is IgA. It provides some protection, but it’s just not as great as IgG.

Q: If newborns get passive immunity from mama during pregnancy, why are they susceptible to illness? 

A: Passive immunity only lasts for a short time. That’s because antibodies tend to not survive very long (a few weeks to a few months, on average). Unfortunately, the effector cells and memory cells that are responsible for making the antibodies in mama do not cross the placenta. The memory cells are the cell types that stick around for years to provide lasting immunity. I read a study that indicated 88 percent of babies of vaccinated mothers have passive immunity to measles at 4 months, and that number dropped to 15 percent by 8 months of age4. Although, and this is important, the amount of antibodies acquired through passive immunity may not be sufficient to protect the baby from a strong pathogen.

Q: What about the alternative vaccine schedule versus the CDC recommended vaccine schedule?

A: I’ve never found evidence to support the alternative vaccine schedule. It is my understanding that it is something to make parents feel more comfortable. There are a lot of factors taken into account for the CDC schedule, which have to do with considerations like when the acquired immunity will be best. For example, MMR is not given until 12 months because they want to make sure that all passive immunity acquired from mama during pregnancy is gone by the time the vaccine is administered because those circulating antibodies would decrease the immune response to the vaccine. So MMR can be given at 6 months, but is better at 12 months…and I recently read a study indicating even a little tiny bit better at 15 months5; but, you could possibly do the initial shot earlier than 12 months and then get the booster early if you are concerned about measles in your community (of course, talk to your doc about these decisions).

I hope this was helpful! Again, I have no financial interest in this debate. As the mama of a 7 month-old baby girl who is not old enough to have MMR, a 2 year-old little boy who only now has partial immunity, and as the stepdaughter to a wonderful man who spent his final 9 months severely immunocompromised due to chemotherapy, I am certainly emotionally invested in the debate. But as a scientist who has read thousands of pages of scientific research, I only want to help spread knowledge and quell fear.

For links to more information about vaccines please check out the blog post just prior to this one.

References

1 Iossifov I, et al., The contributions of de novo coding mutations to autism spectrum disorder. Nature. (2014) 515(7526)

2 De Rubeis S, et al., Synaptic, transcriptional and chromatin genes in autism. Nature. (2014) 515(7526)

3 Bauman MD, et al., Maternal antibodies from mothers of children with autism alter brain growth and social behavior development in the rhesus monkey. Transl Psychiatry. (2013) 9;3

4 De Serres, et al., Passive immunity against measles during the first 8 months of life of infants born to vaccinated mother or to mothers who sustained measles. Vaccine. (1997) 15(6-7):620-3.

5 Hinman A., et al., Comparison of Vaccination with Measles-Mumps-Rubella Vaccine at 9, 12, and 15 Months of Age. J Infect Dis. (2004) 189