The Centers for Disease Control and Prevention said Wednesday that more than 108 million Americans have received at least one dose of the coronavirus vaccine, and that the country is averaging about 3 million vaccinations per day. But for how long will the vaccines be effective? Yahoo News Medical Contributor Dr. Kavita Patel explains.
KAVITA PATEL: Natural immunity develops after infection from SARS-COV-2, coronavirus, or a COVID-19 infection– all the same thing. But that’s really your own body’s kind of way of responding and recognizing that if you were to be exposed again to the virus, you would have antibodies developed. Natural immunity really helps target what infected you in the first place, which could be very different from the strains that we’re seeing today– or similar, depending on what you were infected with.
And the immunity developed from vaccines can actually respond– we call it a polyclonal antibody response, which means that there are multiple exposures to your body through the vaccine which you don’t even realize that helped trigger a very robust B cell and T cell response. Those are different kinds of antibodies, which also get developed after natural infection. But in the case of vaccines, think of it this way. You get more immunity at higher levels and to a wider variety of types of coronavirus spike proteins. So it prepares your body for almost any conceivable type of coronavirus, including the current variants that we’re worried about.
The current vaccines that are authorized in the United States, as well as those in the world, are all effective against the current known variants. When you hear that the vaccines are quote, “not as effective,” it’s when it’s compared to the strains that existed a year ago. But the antibody responses, even in the most potent strains, are still sufficient to overcome the effect of that strain.
So the good news is that any vaccine that’s authorized is going to have an effect on the current variants to prevent death, to prevent severe hospitalization. But of course, this is something that we have to keep a close eye on. And that’s why there’s talk and testing around what we call booster shots, to see if we need to alter the vaccines and give everyone a booster at some point this year.
So there was one of the first what we call real-world evidence data reports released recently from Pfizer, over 4,000 health care workers that were studied and followed up, including some trial participants as well, that showed that immunity lasts at least six months. So we know that from data– which had thousands and thousands of participants just in the United States alone, but also included people from around the world– that antibodies remained at very high levels at least six months after the second dose.
The only reason it’s limited to six months is because that’s the longest period of time that we’ve had to look at people since the vaccine was available or studied in people. There is no reason to believe that the immunity would not last at least 12 months, possibly even longer. And that’s good news, considering some Americans have received the vaccine as early as December and are looking for their immunity to last, hopefully, through the next winter.
So different bodies react very differently. But what we do know is that if you have a two-dose vaccine, the first dose really introduces kind of the message to make a spike protein into your body. Your body goes ahead and makes a spike protein, as well as making antibodies to that spike protein, recognizing it’s foreign.
On the second dose, think of that as its own type of booster, where it reintroduces that exact same message. This time, the body doesn’t need to wait. It recognizes what’s being introduced and made by its cells is that spike protein, and it signals to the entire immune system that this is dangerous, and it triggers a response.
So it does mimic a flu type of illness. And some people have had dramatic fevers, body shakes, and other symptoms. We generally expect for that to last up to 36 to 48 hours and resolve. If it hasn’t resolved, you should talk to a doctor.
Just because you do not have a reaction does not mean that your body has not responded, because every single individual has a varying robust immune response in what it looks like. And if you are really concerned that you did not have a response, talk to your doctor. At the end of the day, immunity is broad, durable, and long-lasting, at least to what we know today.