Current vaccines against COVID-19 provide powerful protection against the disease. Some evidence suggests that when people who have been infected with the original strain of SARS-CoV-2 (the virus that causes COVID-19) are vaccinated against the disease, they develop unusually robust immunity, a phenomenon known as “hybrid immunity.” However, a recent report describes findings that suggest many people infected with SARS-CoV-2 do not develop antibodies to the virus.

The study involved 72 people who had tested positive for COVID-19 but were symptom-free for at least three weeks. The authors of the study tested the participants' blood for the presence of antibodies to the spike protein (the primary infectious particle of the SARS-CoV-2 virus) as well as other viral particles at the time of enrollment and at subsequent follow-up visits. They gathered information regarding the participants' demographics, viral load, and symptom severity.

Two of the participants (3 percent) reported no symptoms, 13 (18 percent) reported mild symptoms, 48 (67 percent) reported moderate symptoms, and 9 (12 percent) reported severe symptoms. The authors' analysis revealed that 36 percent of the participants failed to develop detectable antibody levels against the SARS-CoV-2 spike protein or other infectious particles. Those who did not develop antibodies were on average 10 years younger and had lower viral loads than those who developed higher antibody levels.

These findings indicate that the antibody response to SARS-CoV-2 infection is variable and subject to a variety of factors. Vaccines against COVID-19, on the other hand, provide predictable antibody responses. It is important to note that although antibodies are important components of the body’s immune response, cellular immunity plays a critical role, too. Learn more about COVID-19 vaccines in this clip featuring Dr. Roger Seheult.

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