The measles vaccine has a lifelong effect. The chickenpox vaccine is 20 years old. The DTaP vaccine (diphtheria, tetanus, pertussis) requires five doses until the age of seven, but then provides protection for at least 10 years. Then why do we assume we need to get a dose of coronavirus vaccine every six months or every year? The Jerusalem Post asks. There are reasons why people may need a booster dose of Covid-19 every year, but there are also reasons why the third dose may be – in fact – the last.
The first reason we may need a fourth (fifth or sixth) dose is a decline in antibody count and immune response, says Dr. Oren Kobiler of Sackler University School of Medicine in Tel Aviv.
Why do we need another dose of vaccine?
Recent studies have shown that the Pfizer vaccine is declining after four to six months, which means that people are becoming more vulnerable to infection. And the booster dose boosts the antibodies, providing greater protection against the virus.
Another reason why we may need other doses is the appearance of variants. If the SARS-CoV-2 virus is constantly changing, then our vaccines will need to be updated to protect us from the latest threats.
In contrast, the flu changes every year, so people who want to protect themselves against it get immunized every year.
Coronavirus mutations less often than influenza virus
“The vaccine is protection. The period of protection depends on the vaccine and the virus “, explains Professor Meital Gal Tanamy, head of the molecular virology laboratory at Barllan University School of Medicine.
“A variant is a virus that contains mutations and if it has evolutionary advantages, it can become predominant in the population”, she said, adding that this was the case with the Delta variant.
“The other question is how effective vaccines will be against these variants.”, added Tanamy.
Coronavirus is an RNA virus, which means it changes. However, its mutation rate is three to four times lower than that of the flu virus, which is good news for those who develop vaccines, she said.
Reasons why this third dose might be the last
Many childhood vaccines are given in three inoculations without other doses, such as the polio or HPV vaccine. The latter has three doses, the second one month after the first and the third at six months, and then lasts a lifetime.
Another hypothesis is that the dosing regimen could be modified to make vaccines more effective.
Several recent studies suggest, for example, that the Pfizer vaccine provides a more robust immune response if a 12-week interval is left between the first two doses, instead of three weeks, Kobiler says.
“So with the third dose six months after the second, I don’t think we’ll ever need another booster.”, he said.
Vaccination will probably become useless
There are scientists who believe that, like other coronaviruses, the pandemic will eventually become endemic and less severe, and vaccination will become unnecessary, Kobiler added.
“I am more inclined to this point of view because of what we know about other coronaviruses. They are usually taken at an early age and cause a very mild illness. And those who are exposed to them from an early age tend not to suffer from the severe form of the disease at other ages. “, said the expert.
In conclusion, each booster dose elicits a better immune response, both in terms of quantity and quality, compared to the previous one, according to Gal Tanamy. Thus, the immune response becomes “more precise” and the antibodies “more effective”.
So will we have to be vaccinated against Covid-19 all our lives? “Only time will tell.” Kobiler pointed out.
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