I have been following the COVID-19 news for quite some time now and there is this one thing which is just bugging my head. When I first started seeing the statistics, the death rate was at around 15% and later it peaked around 21%, after which, it started reducing steeply. Why is this?

How is it possible for the death rate to reduce like that? There are a few theories which I came up to rationalize this but all of them seem unlikely

  1. The vaccine was secretly discovered somewhere ( highly unlikely)

  2. The virus mutated to become less serious ( there many strains of COVID)

  3. somehow developed herd immunity


The closed case graph on


  • 1
    People did something against the spreading of the virus to those more at risk of dying from an infection?
    – Thomas
    May 16, 2020 at 14:07

1 Answer 1


I haven't seen any evidence that the actual death rate has changed at all.

See this Q&A: Does COVID-19 have a case fatality rate of 41%? Is this formula correct?

The ratio of "deaths/(recoveries+deaths)" does not describe the actual case fatality rate

Early in the pandemic, when there are lots of new people infected, almost all of the cases were unresolved because most of them were new and it takes a long time to get recovered. Imagine two people are sick, and one dies after 1 week and the other survives but is still sick for another 2 weeks. For those 2 weeks you would find, based on this formula, that the death rate is 100%, because the other case hasn't recovered yet.

Recoveries are not important to health care

In the middle of a severe situation, health care workers are most interested in finding and treating the people who are sick. Sure, it might feel good to be able to mark some people as recovered, but for those who recover on their own at home outside of a hospital, it's a low priority to follow them to find that they have recovered. Therefore, recovery numbers can lag. Some countries, like the UK, don't even report recoveries, so their patients can't be included in the "recovered" category, and if you did the calculation for the UK you'd find 100% deaths.

Only confirmed cases are counted by worldometers

Since the beginning of the outbreak, we've learned there are substantial numbers of asymptomatic people. Because not everyone gets tested, there are lots of missing people who had limited symptoms and recovered easily on their own.

In summary, the actual death rate has probably not changed

There's no secret vaccine, no evidence of mutation making it less severe, and nowhere near enough infected people for herd immunity yet.

It's also nowhere near the 15% or 21% you are citing and never was, except in the oldest and most vulnerable patients.

Note that the source you cite explains some of these things here: https://www.worldometers.info/coronavirus/coronavirus-death-rate/

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.