They Recovered From the Coronavirus. Were They Infected Again?

They Recovered From the Coronavirus. Were They Infected Again?

Can people who recover from a bout with the new coronavirus become infected again — and again?

The Japanese government reported this week that a woman in Osaka had tested positive for the coronavirus for a second time, weeks after recovering from the infection and being discharged from a hospital.

Combined with reports from China of similar cases, the case in Japan has raised some uncomfortable questions. Reinfections are common among people who have recovered from coronaviruses that cause the common cold.

But those pathogens are very different from the new coronavirus, and experts said it’s unlikely that these are cases of people getting infected a second time.

“I’m not saying that reinfection can’t occur, will never occur, but in that short time it’s unlikely,” said Florian Krammer, a virologist at the Icahn School of Medicine at Mount Sinai in New York.

Even the mildest of infections should leave at least short-term immunity against the virus in the recovering patient, he said.

More likely, the “reinfected” patients still harbored low levels of the virus when they were discharged from the hospital, and testing failed to pick it up.

Even if there were occasional cases of reinfection, they do not seem to be occurring in numbers large enough to be a priority at this point in the outbreak.

The Coronavirus Outbreak

  • Answers to your most common questions:

    Updated Feb. 26, 2020

    • What is a coronavirus?
      It is a novel virus named for the crownlike spikes that protrude from its surface. The coronavirus can infect both animals and people and can cause a range of respiratory illnesses from the common cold to more dangerous conditions like Severe Acute Respiratory Syndrome, or SARS.
    • How do I keep myself and others safe?
      Washing your hands frequently is the most important thing you can do, along with staying at home when you’re sick.
    • What if I’m traveling?
      The C.D.C. has warned older and at-risk travelers to avoid Japan, Italy and Iran. The agency also has advised against all nonessential travel to South Korea and China.
    • Where has the virus spread?
      The virus, which originated in Wuhan, China, has sickened more than 80,000 people in at least 33 countries, including Italy, Iran and South Korea.
    • How contagious is the virus?
      According to preliminary research, it seems moderately infectious, similar to SARS, and is probably transmitted through sneezes, coughs and contaminated surfaces. Scientists have estimated that each infected person could spread it to somewhere between 1.5 and 3.5 people without effective containment measures.
    • Who is working to contain the virus?
      World Health Organization officials have been working with officials in China, where growth has slowed. But this week, as confirmed cases spiked on two continents, experts warned that the world was not ready for a major outbreak.