Can you get Covid-19 twice? It’s complicated

After overcoming a battle with Covid-19, President Donald Trump said he was immune to the virus.

Experts say it is possible to get infected again. But it’s rare.

“So 38 million cases worldwide. So far, a few dozen cases of reinfection have been reported, ”said Dr. Soumya Swaminathan, chief scientist for the World Health Organization, told CNN earlier this week.

Dr. Anthony Fauci, director of the National Institute for Allergies and Infectious Diseases, said health officials are starting this week to see “a number of cases” as reinfections.

“Well-documented cases,” he said, “of people who were infected come back after a relatively short period of time from weeks to several months, are exposed and become infected again.”

“So you really have to be careful not to be completely ‘immune’,” said Fauci.

In August, doctors reported that a 25-year-old Nevada man was the first documented case of Covid-19 reinfection in the United States. The man was first diagnosed with Covid-19 in April. After getting better – and testing negative twice – he tested positive for the virus a little over a month later.

A separate research team reported in August that a 33-year-old man who lives in Hong Kong had Covid-19 twice this year: in March and August.

And earlier this year, an 89-year-old Dutch woman who also had a rare white blood cell cancer died after catching Covid-19 twice, experts said. She was the first and only known person to die after being re-infected.

While it is possible to get re-infected with the virus, there are still questions that scientists are working to answer, including who is more likely to get re-infected and how long antibodies protect people from further infection.

Scientists are Investigating how long antibodies last

Several recently released new reports show that immunity to Covid-19 can last for months.

Researchers at the University of Arizona found that antibodies that protect against infection can last for at least five to seven months after a Covid-19 infection.

With the less than a year old pandemic, it will likely be some time before scientists can get a clear picture of immunity.

“However, we do know that people infected with the first SARS coronavirus, which is most similar to SARS-CoV-2, still have immunity 17 years after infection. If SARS-CoV-2 is anything like the first, we expect antibodies to last at least two years, and anything much shorter is unlikely to happen, ”Deepta Bhattacharya, an immunobiologist at the University of Arizona College of Medicine, told CNN.

Other studies, one from Massachusetts and one from Canada, supported the idea of ​​permanent immunity.

This suggests that “a vaccine, if properly developed, may create a sustained antibody response that can help protect the vaccinated person from the virus that causes COVID-19,” said Jennifer Gommerman, professor of immunology from the University of Toronto. said in a statement.

It is unclear how secondary infections can affect a Covid-19 vaccine. The Nevada man had more critical symptoms during his second infection, while the Hong Kong man had no obvious symptoms during his reinfection.

“The effects of reinfection could be relevant to vaccine development and use,” said the authors of a recent study in The Lancet.

Antibodies can affect how severe the disease is

There’s one more thing that researchers have started to notice: people who have a tougher battle with the disease tend to have stronger immune responses.

“There is a difference between people who are asymptomatic and who have had a very mild infection. There seems to be a slightly larger number of people who have no detectable antibodies, ”says Swaminathan of the WHO. “But almost everyone who suffers from a moderate to severe illness has antibodies.”

Bhattacharya of Arizona repeated this statement.

“Those interviewed by the intensive care unit had higher levels of antibodies than those with a milder condition,” he said, adding that he does not yet know what this will mean for long-term immunity.