Our president announced that New Zealand suffered a major surge of Covid-19 on Monday (“big surge in New Zealand, you know it’s terrible, we don’t want that”). They had nine new cases. The U.S. had 42,000. 

For somewhat more reliable information, see this informative summary from StatNews (the article has more about each item):

. . . In the time since Chinese scientists confirmed the rapidly spreading disease in Wuhan . . . an extraordinary amount has been learned about the virus, SARS-CoV-2, the disease it causes, Covid-19, and how they affect us.

Here are some of the things we have learned, and some of the pressing questions we still need answered.

What we know

Covid and kids: It’s complicated 

. . . Everything Covid is complex, and kids are no exception. While deaths among children and teens remain low, they are not invulnerable. And they probably contribute to transmission of SARS-CoV-2, though how much remains unclear. . . 

There are safer settings, and more dangerous settings

Research has coalesced on a few key points about what types of setting increase the risk that an infectious person will pass the virus to others. . . . 

People can test positive for a long time after they recover. It doesn’t matter 

There was a lot of angst a few months ago about some people who had seemingly recovered from Covid-19 infections continuing to test positive for the virus for weeks. Were they infectious? Should recommendations be changed for how long infected people should be isolated? It turns out it is an issue of testing. . . .

After the storm, there are often lingering effects 

Name a body part or system and Covid-19 has left its fingerprints there. . . . There are growing worries that these and other health effects will be long-lasting. . . .

‘Long-haulers’ don’t feel like they’ve recovered

We know they’re out there, but we don’t know how many, why their symptoms persist, and what happens next. . . . 

Vaccine development can be accelerated. A lot

An extraordinary amount of progress toward Covid-19 vaccines has been made, in record time. . . . 

People without symptoms can spread the virus

Whatever group you’re talking about, there are some key implications for the pandemic, and trying to rein it in. . . .

Mutations to the virus haven’t been consequential 

Coronaviruses in general do not mutate very quickly compared to other viral families. This is a good thing . . .  .

Viruses on surfaces probably aren’t the major transmission route

The general consensus now is that “fomites” — germs on surfaces — aren’t the major transmission route for Covid-19. . . .But it’s clear from lots of studies that surfaces around infected people can be contaminated with viruses and the viruses can linger. . . . 

What we don’t know

People seem to be protected from reinfection, but for how long? 

The thinking is that a case of Covid-19, like other infections, will confer some immunity against reinfection for some amount of time. But researchers won’t know exactly how long that protection lasts until people start getting Covid-19 again. So far, despite some anecdotal reports, scientists have not confirmed any repeat Covid-19 cases. . . .

What happens if or when people start having subsequent infections? 

Given that most respiratory viruses are not “one-and-done” infections — they don’t induce life-long immunity in the way a virus like measles does — there is a reasonable chance that people could have more than one infection with Covid-19. . . .

How much virus does it take to get infected? 

Whether you become infected or not when you encounter a pathogen isn’t just a question of whether you’re susceptible or immune. It depends on how much of the virus (or bacterium) you encounter. . . .

How many people have been infected?

There have been 21 million confirmed cases of Covid-19 around the world, and 5.3 million in the United States. Far more people than that have actually had the virus. . . .

It’s not clear why some people get really sick, and some don’t 

The sheer range of outcomes for people who get Covid-19 — from a truly asymptomatic case, to mild symptoms, to moderate disease leading to months-long complications, to death — has befuddled infectious disease researchers. . . .