Thread by @RajeevJayadevan

Approval of vaccine is based on risk vs. benefit analysis in each country.

“The vaccine is something the US desperately needs”

-said the experts of a committee that voted 17:4 in favour of FDA giving EUA.

Why did they decide yes?

See thread. 1/10

amp.usatoday.com/amp/3850826001

Every day in the US, about 3000 people die from COVID-19.

With the graph steadily climbing, a vaccine is something they believe could give them hope.

It is not the same situation in India. Deaths are 414/day for a population of 135 CR.

For US it is 3000/day for 33 CR.

2/10

The pandemic situation in US and India are vastly different.

US death rate is 30 times (yes, that is 3000%) that of India.

That is, for every 1000 citizens, the number of COVID deaths is 30 times more in the US.

See graphs from today.

3/10

In India, the new cases graph & deaths are declining since October. Unfortunately in the US, the graphs are going ~vertically upwards.

All deaths are painful. But these 2 countries are @ significantly different levels of risk. The levels of desperation are different.

4/10

The question is whether a country should rush to give a vaccine before safety is well-established.

When the situation is desperate as in the US, yes - they will be willing to take that extra risk of theoretical harm from vaccine.

Some customization is necessary here.

5/10

But if the situation is less severe, the risk of exposing millions of healthy people to a new product of just 2 months safety-record must be carefully thought of.

The longer we wait, the more certain we will be about vaccine safety. But waiting too long is not an option.

6/10

What makes vaccines different is they’re given to large no. of ~perfectly healthy people.

This is different from a new drug that will only be used in a few people with serious illness; and the chance of anyone getting a serious outcome is small, as the total no. is small.

7/10

The yardstick used to measure side effects is therefore different for vaccines.

The reason for particularly emphasizing vaccine safety is the LARGE number of people who will suffer if we wrongly approve a potentially dangerous vaccine.

8/10

There are no reliable data that vaccines reduce asymptomatic transmission. All efficacy measurements have been on symptomatic COVID-19 only.

If symptomatic transmission is not blocked, the might not be very good at preventing spread in the community. We do need more data.

9/10

There are no indications yet that there is anything dangerous about front-line vaccines. The short term reports are mostly good. But the theoretical risk is always there. The longer we wait, the more no. of people worldwide get to use it; the better we will know the risk.

10/11

Bottom line: For the same vaccine, every country faces a different risk vs. benefit equation.

Vaccines are only 1 method of fighting a pandemic, & will not stop the need for social distancing anytime soon.

A little bit of patience now can’t be a bad thing for India.

11/11

@snehamordani @ridhimb @Milan_reports @soutikBBC @AparnaKurup @Kanjivellam @AnantBhan @NairPreetuTOI @msudhaTOI @BShajan @PRamdas_TNIE @NishaPurushoth2 @nishanigil @Anandans76

*If asymptomatic transmission is not blocked...