Good news
That seems to be true in the case of the man from Hong Kong. When doctors tested his blood to look for antibodies to the virus, they didn’t find any. That could mean that he either had a weak immune response to the virus the first time around, or that the antibodies he made during his first infection diminished over time. But during his second infection, he quickly developed more antibodies, suggesting that the second infection acted a little bit like a booster to fire up his immune system. That’s probably the reason he didn’t have any symptoms the second time, too.
That’s good news, Dr. Poland said. It means our bodies can get better at fighting off the COVID-19 virus and that catching it once means the second time might not be so bad.
But the fact that the virus can change quickly this way does have some impact on the effort to come up with a vaccine that works well.
“I think a potential implication of this is that we will have to give booster doses. The question is how frequently,” Dr. Poland said. That will depend on how fast the virus is changing, and how often reinfection is happening in the real world.
“I’m a little surprised at 4½ months,” Dr. Poland said, referencing the time between the Hong Kong man’s infections. “I’m not surprised by, you know, I got infected last winter and I got infected again this winter,” he said.
It also suggests that immune-based therapies such as convalescent plasma and monoclonal antibodies may be of limited help over time, since the virus might be changing in ways that help it outsmart those treatments.
Convalescent plasma is essentially a concentrated dose of antibodies from people who have recovered from a COVID-19 infection. As the virus changes, the antibodies in that plasma may not work as well for future infections.
Drug companies have learned to harness the power of monoclonal antibodies as powerful treatments against cancer and other diseases. Monoclonal antibodies, which are mass-produced in a lab, mimic the body’s natural defenses against a pathogen. Just like the virus can become resistant to natural immunity, it can change in ways that help it outsmart lab-created treatments. Some drug companies that are developing monoclonal antibodies to fight COVID-19 have already prepared for that possibility by making antibody cocktails that are designed to disable the virus by locking onto it in different places, which may help prevent it from developing resistance to those therapies.
“We have a lot to learn,” Dr. Poland said. “Now that the proof of principle has been established, and I would say it has with this man, and with our knowledge of seasonal coronaviruses, we need to look more aggressively to define how often this occurs.”
A version of this article originally appeared on WebMD.com.