This rapid drop in protection has major implications for India's vaccination programme.
The world is facing an uphill struggle against Covid - and in India there is a fear that a 3rd wave could hit us soon. Now, new global research overturns some earlier beliefs about Covid and vaccinations. These findings suggest that our fight against Covid is going to be even tougher than it already is.
Global research has established that protection by vaccines doesn't last long - nowhere near a full year, as previously hoped. It is now clear that the efficacy of all vaccines drops sharply every month after a person is fully-vaccinated.
The Pfizer vaccine starts with a 95% level of protection, but in just 4 months, it drops to a disappointing 48%.
The Astra-Zeneca vaccine, known in India as Covishield, starts with a 75% level of protection - and drops over four months to a poor 54% efficacy.
This rapid drop in protection has major implications for India's vaccination programme.
The most important impact is an immediate and urgent need for booster (or third) shots. With vaccine protection dropping below 50% in 4 to 5 months, it is essential to have a booster six months -or, at the most, 8 months - after the second dose.
India needs to begin booster vaccine doses immediately. First for doctors, nurses and all our frontline workers. Second, for the 60+ population and those with co-morbidities. And finally, for those in the general population who have been fully vaccinated.
Already 150 million people have had two doses and will need a third booster shot. The number of booster shots required will increase every month.
Perhaps an even more disturbing finding of new global research is that an increasing number of children, who have so far been considered less vulnerable, are now being infected by the Covid virus.
In Britain, over the last few weeks, there has been a sharp rise in the positivity rate among children. Alarmingly, almost 45% of boys in the age range of 10 to 19 are testing positive for Covid, and
even younger boys between the ages of 4 and 10 have a positivity rate as high as 35%. For girls, it is not much better: between the ages of 5 and 19, they have a positivity rate of 35%.
Based on these findings, India needs to also focus on vaccinating the 450 million girls and boys between the ages of 5 and 19.
This is a massive new task but an extremely important and urgent need in our fight against Covid.
Given our current rate of vaccinations, and with this new need for booster shots and vaccines for our children, it is estimated that India will only reach a target of fully protecting 60% of its population by the end of next year- December 2022.
This makes us vulnerable to a third and even a fourth wave.