Prior infections with some seasonal human coronaviruses might protect against severe COVID-19.
Coronaviruses are named for the crown-like spikes (‘corona”) on their surface. Human coronaviruses (HCoVs) were first identified in the mid-1960s. The first four coronaviruses identified that can infect people are: 229E, NL63, OC43, HKU1 – all causing the common cold. People around the world commonly get infected with 229E, NL63, OC43, and HKU1.
Sometimes coronaviruses that infect animals can evolve and make people sick and become a new human coronavirus. Three recent examples of this are human coronaviruses SARS-CoV (the coronavirus that causes the severe acute respiratory syndrome, or SARS), MERS-CoV (the coronavirus that causes Middle East Respiratory Syndrome, or MERS), and SARS-CoV-2 (coronavirus that causes COVID-19).
According to a German study published in the International Journal of Infectious Diseases, patients critically ill with COVID-19 infections had significantly lower levels of antibodies against seasonal HCoVs: OV43 and HKU1 than those with mild to severe infections.
The researchers say the results could indicate that prior infections from seasonal coronaviruses, which frequently present as mild pediatric respiratory tract infections, may help prevent severe COVID-19 illness.
University Hospital of Munster researchers drew serum samples from 60 people with confirmed COVID-19 infections. Participants included outpatients (41.7%), hospitalized patients with severe or moderate disease (26.7%), and hospitalized patients with the critical disease (31.7%). Outpatients were selected to match inpatient sex and age as best as possible. The median age of outpatients and those with critical illness was 58 and 55 for in-patients with severe or moderate illness.
Patients with lower levels of HCoV OV43 and HKU1 antibodies (P = 0.016 and 0.023, respectively) were more likely to have longer hospitalization periods. The overall median length of stay was 10 days (range, 2 to 55). Three deaths occurred.
While HCoV OC43 and HKU1 immunoglobulin G (IgG) antibodies were significantly lower in critical COVID-19 patients, these same patients had higher levels of antibodies against COVID-19. Researchers suggest that the possible protection HCoV OC43 and HKU1 infers is due to T cell-based immune response, but they acknowledge more research is needed in this area.
A similar study published in the journal Science in December 2020 found that a small subset of people — and a higher proportion of children compared with adults — carried antibodies from previous coronavirus infections that had the ability to neutralize SARS-CoV-2. It is possible that pre-existing immune memory cells could potentially provide some level of protection or reduce the disease severity of COVID-19.
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Dr. Melvin Sanicas (@Vaccinologist) is a physician-scientist specializing in vaccines, infectious diseases, and global health.