According to a study conducted by AIG hospitals along with Asian Healthcare Foundation among 1,636 fully vaccinated individuals, 30% of the surveyed people lost immunity generated in response to COVID-19 vaccines after 6 months.

Investigators assessed the IgG anti-S1 and IgG anti-S2 antibodies to SARS-CoV-2 in the study participants. Those with antibody levels less than 15 AU/ml were considered antibody negative. A level of 100 AU/ml was considered the minimum level for protection against the virus. The level to which immunity declines was directly proportional to the age of the individual, suggesting that younger people had sustained antibody levels compared to the elderly. People over 40 with co-morbidities had significantly less antibody response after six months of receiving the second vaccine dose… (ET Healthworld – Deccan Herald, January 19, 2022)