How many times can we get infected with the coronavirus?

More than 404 million cases have been infected with the severe acute respiratory virus coronavirus 2 (SARS-CoV-2), with 5.8 million confirmed deaths as of February 2022. South Africa has experienced four waves of SARS-CoV-2 transmission. 2, with the second, third, and fourth waves being powered by the Beta, Delta, and Omicron variants, respectively. A key question with the emergence of new variants is the extent to which they can reinfect those who have had a previous natural infection. The core problem is that the coronavirus has become more adept at reinfecting people. Those infected with the first Omicron variant are already reporting second infections with the newer versions of the variant: BA.2 or BA2.12.1 in the US, or BA.4 and BA.5 in South Africa. Those people may have a third or fourth infection, even within this year. And a small fraction may have symptoms that persist for months or years, a condition known as prolonged Covid. “It seems likely to me that this will be the long-term pattern,” says Juliet Pulliam, from the University of Stellenbosch (South Africa), in a paper published in the journal “Science.” The researchers developed two approaches to monitor epidemiological surveillance data to determine whether the risk of SARS-CoV-2 reinfection has changed over time in South Africa in the context of the emergence of Beta (B.1.351), Delta (B.1.617.2) , and Omicron (B.1.1.529). “We considered people who had sequential positive tests at least 90 days apart to have suspected reinfections,” she explains. The Omicron variant is associated with a marked ability to evade immunity from a previous infection. In total, they identified a total of 105,323 suspected reinfections among nearly three million people with confirmed SARS-CoV-2. As they write in “Science”, population-level evidence suggests that the Omicron variant is associated with a marked ability to evade immunity from a previous infection. However, there is no population-wide epidemiological evidence of immune escape associated with Beta or Delta variants. “This finding has important implications for public health planning, particularly in countries like South Africa with high rates of immunity from prior infection.” If reinfection turns out to be the norm, experts predict that the coronavirus will not just be a once-a-year thing during the winter. The study describes that the number of reinfections with previous variants, including Delta, was relatively rare. But in September, it seemed to accelerate and was notably high in November, when the Omicron variant was identified. According to this work, an infection with Omicron produces a weaker immune response, which appears to decline rapidly, compared to infections with previous variants. Although the newer versions of the variant are closely related, they vary enough from an immunological perspective that infection with one doesn’t leave much protection against the others, and certainly not after three or four months. Most people who get reinfected with new versions of Omicron will not get seriously ill Still, the good news is that most people who get reinfected with new versions of Omicron will not get seriously ill. At least for now, the virus hasn’t found a way to completely bypass the immune system. “The virus is going to continue to evolve. And there are probably going to be a lot of people who get many, many reinfections throughout their lives,” Pulliam told NYT.