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Does COVID-19 Count as a Vaccine Dose? Information for Pregnant Women

For more than a year, we have to devoted a great deal of discussion to the COVID-19 vaccines of Pfizer-BioNTech and Moderna, and also to other COVID-19 vaccines, such as the COVID-19 vaccines of Janssen (Johnson and Johnson), AstraZeneca/Oxford, and Novavax. But you may also be hearing about an idea that ‘natural immunity’ —meaning immunity resulting from actually getting infected with SARS-CoV2 (the virus that causes COVID-19) is better than what you develop after a jab of a vaccine. Or, you may be hearing that the vaccines produce better immunity than natural immunity. The terminology itself is misleading, since the immunity that you develop as a result of vaccine jabs also is natural immunity. There is an expression that goes “Nature has a very good public relations department”, which certainly seems to apply here. Furthermore, often the discussions are framed in an all-or-nothing context, because the issues surrounding the pandemic, sadly have become so politicized. But the answer —which applies to you whether you are pregnant or not— lies somewhere in the middle.

When you are infected with SARS-CoV2 for the first time, your immune system gets a glimpse of the virus. From the viewpoint of the immune system, this is similar to what happens when you receive your first vaccine jab, if you haven’t already had a SARS-CoV2 infection, though not exactly the same. In the case of a SARS-CoV2 infection, a few different molecules on each virion (virus particle) have multiple sites called epitopes, each of which can stimulate the immune system, although they don’t all stimulate the immune system with the same amount of strength. One type of molecule, a protein called the spike glycoprotein projects from the virus and has certain epitopes that scientists know are especially good and provoking an immune response. Consequently, vaccine researchers have developed vaccines that cause body cells to produce the viral spike protein, without the rest of the virus, and slightly modified to produce an even better immune response. The approved vaccines provide target practice to the immune system against the spike protein, and especially to the region of the spike protein that sticks to body cells deep in the body, such as in the lungs. Consequently, the vaccines are very effective in preventing severe and moderate COVID-19 disease.

On the other hand, infection with SARS-CoV2 (with or without symptoms that would classify it as COVID-19) produces a more broad immune response. This means an immune response against all of the epitopes on the various molecules on the virus. As with other infectious diseases, this produces immunity that is protective. The debate has been over the amount of immune protection one develops. It gets very complicated, because, unlike a vaccine jab, which gives you a particular, measured quantity of a substance, the amount of virus that infects people varies widely from case to case. But the immune responses do add up together. Thus, for example, if you suffer a bout of COVID-19 and later you receive your first vaccine dose, your immune system reacts as if you are getting your second dose, and also as if your first dose was an overdose. This is because each vaccine dose build upon the previous dose, because that previous dose caused the immune system to make memory cells, so now a larger number of immune cells are available to respond to the next encounter with either the virus, or something designed to mimic the virus. Then, after your second vaccine dose, your immune system reacts as if this were your third dose, and, as if you received your third dose far too early. Scientists have hypothesized that this is the reason why increased rates of typical vaccine reactions, such as soreness, fever, chills, headache, and fatigue, and such reactions appear to be worse, on average, following vaccine jabs in people who have actually been infected previously with SARS-CoV2, and especially those who previously have suffered COVID-19 disease. This phenomenon could justify reducing the number of vaccine jabs recommended for people who already have some immunity on account of having suffered COVID-19.

This also brings up the topic of pregnancy, which in previous posts we have explained is a risk factor for the development of severe COVID-19, even if you are otherwise completely healthy, meaning no ‘co-morbidities’, meaning other medical conditions. If you are pregnant, you have an elevated risk of developing severe COVID-19 than you would have if you were not pregnant, so there is more of a need for an extra vaccine dose. This applies, even if you have suffered a case of COVID-19 and subsequently received one vaccine jab. But that second jab would be like a third jab, since your COVID-19 took the place of the first jab. But there are a lot of unknowns. The immune response may be slightly less robust, in which case it wouldn’t hurt to get that third shot, though you might want to stretch out the time between doses.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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