Study: SARS-CoV-2 reinfections have similar severity to initial infection
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Key takeaways:
- If an initial infection of SARS-CoV-2 causes severe COVID-19, it is more likely that a reinfection will cause severe disease again.
- Long COVID is more likely to occur after an initial infection than after a reinfection.
The severity of a SARS-CoV-2 reinfection is likely to be similar to the severity of a patient’s initial infection, researchers found.
Or, as the NIH explained in a press release about the new study, “severe infections from the virus that causes COVID-19 tend to foreshadow similar severity of infection the next time a person contracts the disease.”
Additionally, researchers found that lower levels of albumin could indicate a higher risk for infection and a greater risk for long COVID after an initial SARS-CoV-2 infection compared with a reinfection.
“Although the COVID-19 pandemic has persisted for over 3 years, reinfections with SARS-CoV-2 are not well understood,” Emily Hadley, MS, a research data scientist at RTI International, a nonprofit research institute, and colleagues wrote in Communications Medicine.
Roughly one-third of SARS-CoV-2 reinfections are missed by clinical assessments and reinfection rates are thought to be higher than official counts because of home testing and unreported infections.
To gauge the severity of disease after reinfection, as well as some of the effects of reinfection, Hadley and colleagues analyzed data from more than 3 million participants in the National COVID Cohort Collaborative (NCCC).
Among more than 213,000 people who reported an initial SARS-CoV-2 infection between March 1, 2020, and Dec. 31, 2022, and a second infection by March 2023, more than 203,000 had two infections and 478 experienced at least three infections.
According to the study, 6.9% of participants in the entire NCCC cohort experienced a second infection, which was higher than the previously reported 5.5%, though the researchers noted that both are “likely” an underestimate because of the increasing availability of home tests during the study period.
Most patients in the analysis did not have an ED visit or hospitalization during their initial infection or reinfection.
Roughly 27% of patients with severe COVID-19 — which the researchers defined as receiving hospital care — were also treated at the hospital for a reinfection.
Conversely, 87% of people with mild cases that did not require hospital care during their first infection had mild reinfections, though Hadley and colleagues wrote that the rate of patients with mild initial infections who visited the ED (33.1%) also went to the ED with a reinfection — a larger proportion of people than those who had a moderate or severe initial infection or reinfection.
Reinfected patients also tended to be younger, were more likely to have documented race and ethnicity information and were less likely to have been vaccinated against COVID-19 at the time of reinfection than those who were not reinfected.
Additionally, the researchers reported that, regardless of variant, patients were more likely to experience long COVID after an initial infection than after a reinfection and that persistently lower levels of albumin after initial infection may increase the risk for reinfection.
“Our work highlights the prevalence and impact of reinfections, and suggests the need for further research,” Hadley and colleagues wrote.
References:
- Hadley E, et al. Commun Med. 2024;doi:10.1038/s43856-024-00539-2.
- Study suggests reinfections from virus that causes COVID-19 likely have similar severity as original infection. https://www.nih.gov/news-events/news-releases/study-suggests-reinfections-virus-causes-covid-19-likely-have-similar-severity-original-infection. Published July 11, 2024. Accessed July 12, 2024.
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