Could COVID-19 be less "dangerous" by the pass of the time, say for instance, on August?

By dangerous I mean, less aggressive in terms of the symptoms, mortality, less probability of caught the virus, etc.

And if it will decrease its potency, by how much approximately?

This virus has already 3 months on earth and we can see it's still as bad as it was in the beginning, even still could be possible that within 5 months or more, which leads to 8 months on earth, might decrease its 'power'?

  • 1
    Nothing can be said about this particular pandemic, but see biology.stackexchange.com/questions/90636/… Note, however, that the processes Ben Bolker describes in his answer there are not really "by August" sorts of processes, these are considering a long-term view. Apr 4 '20 at 0:11
  • 2
    Opinion is still evidence in medical science. I don't see why this was closed as we have good theoretical data on this. Apr 4 '20 at 0:16
  • 2
    Is it relevant whether I or someone else chooses to answer this question? Apr 4 '20 at 0:22
  • 1
    @America if it's important to you to know what might happen you can bounty the question to get more answers. Apr 4 '20 at 0:42
  • 1
    Rep is just fake points. You don't get anything from them. Apr 4 '20 at 0:55

Changes in the virulence of the SARS-CoV-2 will be driven by evolutionary pressure. We know so far that the virus is mutating slowly

The COVID-19 virus does not mutate very fast. It does so eight to 10 times more slowly than the influenza virus, said Anderson, making its evolution rate similar to other coronaviruses such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS).

but there is currently no evolutionary pressure to select out any one strain over another because they are so similar

The virus mutates so slowly that the virus strains are fundamentally very similar to each other,” said Charles Chiu, a professor of medicine and infectious disease at the University of California, San Francisco School of Medicine.

For a virus to mutate to become more lethal does not make evolutionary sense. If it kills its host faster than currently, which would imply a shorter incubation period due to a higher replication rate, then it will reduce its ability to spread which is counter to evolutionary survival.

In fact we have data from a highly lethal rabbit virus that was accidentally released into the wild in Australia. It was almost 100% lethal but eventually the virus mutated to a less virulent form presumably because it had been killing too many of its hosts

The work showed that the almost invariably lethal progenitor virus strain was replaced within a few years by strains with case fatality rates of 70 percent to 95 percent. Some field isolates killed fewer than half the lab rabbits. Over the next few decades, things settled down, and strains at both ends of the lethality spectrum become increasingly difficult to find. Fenner showed why. The highly lethal progenitor virus killed rabbits so fast that its infectious period was shorter than that of the less lethal viral mutants. That meant that the less lethal strains were able to infect more new victims and spread throughout the population.

The rabbits also became more immune to the virus because again of evolutionary pressure and the virus mutated to overcome this resistance. But, we are not seeing any evolutionary pressure on account of SARS-CoV-2 because it's mainly decimating the older population who are past their reproductive lives.

The only evolutionary pressure on the virus I can imagine is if by widespread testing of more symptomatic individuals one might be taking out the more virulent strains letting a less virulent strain to persist in the population. However, the virus's slow mutation rate may prevent that.

Mutation data is being uploaded to a website called NextStrain.org that shows how the virus is migrating and splitting into similar but new subtypes.



  • Thank you for your answer Graham Chiu Apr 4 '20 at 1:25
  • "If it kills its host faster than currently, which would imply a shorter incubation period due to a higher replication rate, then it will reduce its ability to spread which is counter to evolutionary survival" I understand the if part but not the then part. Why will reduce its ability to spread? isn't gaining 'territory' by killing and its higher replication rate? Apr 4 '20 at 1:28
  • If you kill your host, you don't get a chance to replicate. Apr 4 '20 at 2:57
  • I'd add that evolutionary pressure on viruses to become less lethal only arises when hosts start to become scarce. At this point there are still plenty of living humans, so there's no such pressure on SARS-CoV-2 yet. Unlike the rabbit virus, SARS-CoV-2 doesn't kill most people, so this isn't likely to change. Apr 4 '20 at 18:30
  • And also the virus mutates to become more lethal when the host develops immunity to it. So, the rabbit virus learnt to shut down immune responses so it could infect those immune to it. Apr 4 '20 at 20:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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