Coronavirus, COVID-19: What we’ve learned

The coronavirus pandemic began in China last year and hit the world’s radar in January.

Two months later, the virus has spread to nearly every country, infecting more than 400,000 people and killing over 18,000.

Scientists say they still have a lot to learn about the brand-new pathogen, but some things are coming into focus.

If I get sick and recover, will I be immune from COVID-19?

Yes, at least to some extent. Scientists are still learning what happens to the people who survive COVID-19, but there is widespread belief that people who recover will develop a level of protection.

“I think that’s what happens. They develop antibodies, they clear the virus and are likely resistant to future infections. But I guess we’ll learn more in a few weeks,” said Peter J. Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine.

Deborah Birx, the U.S. coronavirus response coordinator, said these types of viruses “constantly mutate” but tend to have a consistent structure, so “if you make effective antibody, you shouldn’t get re-infected.”

New York Gov. Andrew Cuomo has suggested that younger, healthier people and those who recover from the virus might be candidates for going back to work, first, when the state decides to rev up its economy again after weeks of isolation.

He said he would like to see widespread serological tests that determine who has built up antibodies.

Scientists say it will be important to determine the level of protection that returning workers enjoy and whether they can still transmit the disease.

“With other coronaviruses, reinfection without symptoms can occur and there is likely an element of contagiousness. It will be important to understand if this phenomenon occurs with the novel coronavirus,” said Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security.

Are COVID-19 patients really losing their sense of taste and smell?

Yes. In a quirky development, it’s becoming clear that COVID-19 is causing many people to lose their sense of smell or taste.

Researchers in Italy and South Korea have documented the trend, and anecdotal evidence of it is pouring in on social media and elsewhere.

The American Academy of Otolaryngology-Head and Neck Surgery this week said the symptoms should be used to identify patients.

“Anosmia, in particular, has been seen in patients ultimately testing positive for the coronavirus with no other symptoms,” it said, referring to the loss of smell. “We propose that these symptoms be added to the list of screening tools for possible COVID-19 infection.”

Will summer knock this thing out?

President Trump made a prediction about the coronavirus in mid-February, telling governors: “A lot of people think that goes away in April with the heat, as the heat comes in. Typically, that will go away in April.”

It’s almost April, and the pandemic is cresting, but there is reason to believe the changing seasons could diminish transmission.

Coronaviruses, by and large, tend to circulate seasonally. Humidity is one factor, as droplets from coughs and sneezes that spread the virus tend to drop to the ground faster in warmer months.

Also, respiratory diseases spread efficiently in the winter “not necessarily because of the temperature, but because human beings come together in closed environments and therefore transmission is more facilitated,” Mike Ryan, director of the World Health Organization’s emergencies program, said this month.

Scientists said because COVID-19 is so new, it’s hard to predict with certainty whether the virus will burn out this summer. It may slow down but not go away completely.

“While we do not know specifically about this coronavirus, there is reason to believe it will behave like its family members — although the seasonality may be less pronounced because there is no population immunity,” Dr. Adalja said. “If cases are occurring in the summer, it will be at a time when there is less influenza so hospitals may be burdened less with respiratory illnesses.”

Where did this virus come from?

The outbreak likely began at a live-animal market in Wuhan, China, renewing debate about those “wet markets” and whether Chinese authorities need to crack down.

Experts say bats are a natural reservoir for coronaviruses, yet it’s not clear whether the virus jumped directly to people or if intermediate animals were involved.

The West African Ebola outbreak of 2013-2016 was traced back to a boy in Guinea who played near a hollow tree with bats in it. However, civet cats appeared to carry SARS in 2002-2003, while camels were linked to Middle East Respiratory Syndrome (MERS).

This time, “the pangolin has been implicated, but it’s still unclear whether the virus cycled through other animals,” Dr. Hotez said.

Pangolins are scaly anteaters that are illicitly traded in China for medicinal purposes.

Genetic analyses haven’t confirmed pangolins as a culprit, leading to fears they will be slaughtered en masse for no reason.

Is the virus changing?

Scientists have detected some mutations in the virus, though it hasn’t meant much in real-life terms.

“Pretty much this virus, with some variation, has been playing out in the U.S. the way it has in China and Italy,” Dr. Hotez said.

In those countries, the virus had the harshest impact on older people and the medically vulnerable, though young people also have become sick.

Health workers are at particular risk, which was true of the SARS outbreak, too.

“It may be the crowding, it may be higher levels of virus in severely ill patients,” Dr. Hotez said. “I don’t think we really know.”