Measles and COVID-19 are caused by two of the most contagious viruses on the planet. When most people recover from measles the immunity acquired is likely to last for the rest of their lives. This is not true for people who recover from COVID-19. Some people have already been infected with COVID-19 at least four times since the pandemic started a few years ago.
COVID-19 is a new disease. We are still learning how often, or how many total times, someone can be infected, and what health outcomes reinfection causes. Many health experts initially thought immunity from vaccination or infection would slow down reinfections. Omicron changed that.
The 1918 flu pandemic killed at least 50 million people globally, and it came and went in waves. The seasonal flu we experience today spreads during winter when people are more often indoors. Many scientists thought the virus that causes COVID-19 would come and go in waves like the flu, and it’s possible that may happen in the future. But for now, we have experienced sustained and increased transmission of COVID-19, especially since the arrival of the Omicron variant in December 2021.
Unlike the flu, COVID-19 has behaved more like other coronaviruses that cause the common cold and infect people year-round. The reasons for this are not fully known. It is, in part, because Omicron is significantly more contagious than the flu. It’s also because the virus is highly effective at evading immunity and reinfecting people who have had previous strains.
At this time, studies looking at COVID-19 reinfections are ongoing. There are simply not enough data yet to say with any degree of certainty why people get reinfected so often, or how many times someone can get reinfected. Preliminary findings not yet peer-reviewed suggest that the more times someone is reinfected, the potential for more severe illness increases.
Omicron BA.5 is the predominant variant in Oregon and the United States. It’s also the most contagious variant, and it evades vaccine-acquired immunity better than any variant to date. BA.5 can also evade immunity acquired from infections, including from Delta and earlier Omicron variants BA.1 and BA.2. It’s not thought to be more severe than BA.1 and BA.2, and it appears less severe than Delta. However, BA.5 still causes hospitalizations and death. The best thing you can do to reduce your chance of severe disease is to remain up to date on your vaccinations. You may consider waiting up to 90 days after an infection before receiving the next dose you’re eligible for.
“The fact that some people have already had COVID-19 four times in just over two years is concerning,” said Dr. Paul Cieslak, senior health advisor and medical director of communicable diseases and immunizations program at Oregon Health Authority.
Although the vaccines have kept many people alive and out of the hospital, after two and a half years, many people are still getting infected. And reinfected.
“This virus is not going anywhere in the foreseeable future, and it may be with us for the rest of our lives,” Cieslak said. “Preventing its most serious consequences must be a priority going forward.”