Some will get Covid even after vaccination, and that’s normal
No vaccine guarantees 100% immunity from the novel coronavirus, so a small percentage of people who have received a vaccination will still get sick, but experts say that their symptoms are likely to be mild
Abhilash.Gaur@timesgroup.com
01.04.2021
On March 18, Pakistan Prime Minister Imran Khan took his first dose of a coronavirus vaccine made by the Chinese company Sinopharm. On the 20th, he tested positive for Covid. Vaccine-sceptics felt vindicated, China-bashers shouted ‘hurray’. Both were wrong. A vaccine is like a trainer. It needs several weeks to train your immune system to fight a germ. Khan’s first dose got hardly two days to work. In fact, Khan most probably had the virus for several days before he took his shot.
So, Imran Khan’s positive test does not mean his vaccine failed, but are there other cases where a coronavirus vaccine has ‘failed’ to do its job? Is it possible for you to get Covid after vaccination?
Yes, a small percentage of properly vaccinated people are expected to get sick with the coronavirus. Now that many millions have been vaccinated around the world, such cases are becoming common. Why does this happen, and is it fair to describe it as a failure of the vaccine?
Breakthrough Cases
An infection that occurs after vaccination is called a ‘breakthrough case’. But there’s a condition: it should occur at least 14 days after you are “fully vaccinated”. In India, it would mean two weeks after your second dose of Covishield or Covaxin.
Amesh A. Adalja at the Johns Hopkins Center for Health Security tells Prevention magazine that this time-frame is necessary because “your body should have enough time to develop antibodies to SARS-CoV-2 (the coronavirus).”
In a Forbes column, scientist William A. Haseltine mentions Israeli research that found vaccinated and unvaccinated people were equally likely to get infected in the first 12 days after the first vaccine dose. Even after 17 days, 60-80% of vaccinated people could get infected.
The Atlantic’s science journalist Katherine J. Wu says breakthrough cases will now “continue to grow in number, everywhere… They are an entirely expected part of any vaccination process.” You might hear of them in your circle. But the important thing is to not get alarmed and start doubting vaccines.
No Vaccine Is Perfect
Actually, there was a vaccine that provided 100% immunity against the virus it was aimed at, says Bloomberg’s pharma industry analyst Sam Fazeli. It was so good that it totally wiped out the smallpox virus. But such ‘sterilising immunity’ – stopping not only sickness but also infection – is rare.
For the coronavirus, scientists last year set the bar low at 50% efficacy. Luckily, all of the approved vaccines turned out to be far better with efficacy rates as high as 95%. Yet, even the best vaccine can’t guarantee you won’t fall ill.
Again, Wu reminds you this is not a failure of vaccines because “the goal of vaccination isn’t eradication, but a détente in which humans and viruses coexist, with the risk of disease at a tolerable low.”
With vaccines, we are mainly trying to prevent severe disease and death, not the infection itself, and all of the approved vaccines seem to be excellent at that. For example, the singledose Johnson & Johnson vaccine showed only 72% efficacy in US trials, but nobody who took it needed hospitalisation or died.
As Fazeli says, “You will never know how bad your symptoms would have been if you had not been vaccinated.”
Reducing Risk
So, the main reason for breakthrough cases is that vaccines are not perfect. Haseltine says, “we need to draw a distinction between infection and disease” while talking about coronavirus vaccines. As none of the present vaccines claims to protect you from infection, breakthrough cases aren’t surprising. But what makes some vaccinated people more susceptible to the virus than others? Wu says there could be many factors, from your immune system’s response to the virus variant you are exposed to. As the existing vaccines are based on last year’s coronavirus variant, they might be less effective against the newer variants.
Haseltine says a study from China found that “sera from those infected by the original Wuhan strain last year have little to no ability to protect against either the UK (B.1.1.7) or the South African (B.1.351) strains.” Also, your immune system could buckle under the force of a big virus dose, for example inside a room where many Covid patients are present. “Large doses of the virus can overwhelm the sturdiest of immune defences, if given the chance,” Wu says.
That’s why continuing to wear a mask even after you have been vaccinated can reduce the risk of breakthrough cases. Especially now, when coronavirus infections are sharply rising across India.
