Covid-19: Prolonged or severe illness leads to higher antibody levels, study finds

People with severe or long-lasting Covid-19 symptoms are more likely to develop high antibody levels needed to fight future infections, a new Rutgers University study has found.

The paper, published in The Journal of Infectious Diseases, was part of the larger Rutgers Corona Cohort study that followed 83 people, including 548 health care workers, from the beginning of the pandemic.

Within six months of the study’s start, 11 per cent or 93 participants tested positive either for SARS-CoV-2 or for its antibodies. Of those, 24 suffered severe symptoms while 14 were asymptomatic. A third of the infected participants displayed symptoms such as shortness of breath, fatigue, and loss of smell and taste that lasted a month at least. Ten per cent displayed symptoms that lasted around four months.

Most people who get infected by the virus develop antibodies. According to the study, however, antibody production varies on the basis of severity of the symptoms — 96 per cent of the participants who displayed severe symptoms developed IgG antibodies against 89 per cent with mild-to-moderate symptoms and 79 per cent asymptomatic.

The study’s co-lead author Daniel B. Horton said neurological changes such as brain fog and problems with vision or memory, although infrequent among the infected participants, tended to last many months when they occurred.

Higher antibody levels over a period of time were also associated with persistent symptoms, Horton said in a Rutgers University release. The researchers discovered from other research that vaccines enhanced immune protection further, sometimes even helping ease long-term symptoms.

Emily S. Barrett, Co-lead author, said antibody levels declining over time was a normal occurrence. However, IgG antibodies provided long-term protection to help fight reinfection.

The participants in the study were recruited before they were infected by the SARS-CoV-2 virus. It evaluated people across illness severity and provided a broad insight into long-term antibody response.