Studies show long-term COVID-19 immune response

Persistence of the immune response to SARS-CoV-2, the virus that causes COVID-19, is important for understanding community outbreaks and serological test data and predicting the longevity of vaccine protection. Two new studies show how the severity of the disease predicts long-term antibody production, detailing how immunity declines over time, but can exist for up to 7 months. There is sex.

Severe illness and persistent immune response

United Kingdom Investigation To Nature microbiology Today, we surveyed 65 individuals with SARS-CoV-2 infection and 31 serum-positive health care workers (HCWs) identified by the polymerase chain reaction (PCR).

The authors of the study used enzyme immunoassays to sample patients with asymptomatic to severe symptoms for antibody responses in serum collected up to 94 days after the onset of symptoms.

More than 95% of patients showed seroconversion (presence of detectable SARS-CoV-2 antibody) and neutralizing antibody in the sample 8 days after the onset of symptoms, but the magnitude of the neutralizing antibody response was of disease. It depends on the severity and seems to have low peak antibodies. Individual level indicating mild illness.

Researchers have found that the SARS-CoV-2 antibody response is typical of other acute viral infections, with levels decreasing following the initial peak antibody response. Immunoglobulin (Ig) A and IgM antibodies approached baseline levels in some patients by 60 days after onset of symptoms and remained high in IgG in most patients until 94 days after onset.

In some individuals with low initial levels of peak neutralizing antibodies (mean infection level) [ID₅₀], 100-300), antibody could not be detected after 50 days, but some patients with high initial levels (ID)₅₀, 1,000-3,500) maintained neutralizing antibodies for more than 60 days after initial symptoms.

“In some individuals, SARS-CoV-2 infection produces only a rapidly diminishing transient neutralizing antibody response,” the authors suggest. In contrast, antibody levels (ID) in patients with high initial levels₅₀ > 4,000) decreased, but remained in the range of 1,000 to 3,500 until the end of the study period.

Antibodies up to 7 months after infection

Similar findings came from Portuguese Investigation Last week European Journal of Immunology It investigated antibody levels in more than 500 inpatients, health care workers, and volunteers who recovered from COVID-19. Researchers have found that 90% of SARS-CoV-2 positive individuals have antibodies that are detectable from 40 days to 7 months after infection, which is higher in more severely ill patients. ..

The study also found that antibody levels rose rapidly in the first three weeks after symptoms appeared. Although IgA and IgM antibody levels declined over time, researchers discovered virus-neutralizing activity and detectable IgG antibodies for at least 6 months after SARS-CoV-2 infection.

Males had high antibody levels during the acute phase, but levels balanced between genders months after infection. No significant difference by age group was found in antibody production.

“Although antibody levels have been observed to decline over time, neutralization assay results show strong neutralization activity up to 7 months after infection in most subjects previously screened for virus positive. “I showed,” Reed explained. Authors Marc Veldhoen, PhD, Instituto de Medicina Molecular, Lisbon, news release..

The authors conclude that most people infected with SARS-CoV-2 have protective immunity to the circulating virus for months after the initial infection.