On November 22, 2021, Dr. Balram Bhargava said there is no scientific evidence so far to support the need for a booster vaccine dose against COVID-19. The priority was on administering the second dose to all adults. No new evidence from India has become available to support an additional dose after Dr. Bhargava's assertion. There … Continue reading The basis on which India approves precaution dose remains unclear
T cell memory
Covaxin elicits immune memory to virus up to six months, study finds
The study conducted on 39 individuals who received two doses of Covaxin found that the vaccine induces memory T cells in about 85% of the subjects. The T cell responses are largely preserved against the variants, including the Delta variant. A small study conducted on 71 individuals who received two doses of Covaxin found that … Continue reading Covaxin elicits immune memory to virus up to six months, study finds
COVID-19: Protection against reinfection may last only for months
A longitudinal cohort COVID-19 study undertaken in India has found that infected people lack meaningful immunity against SARS-CoV-2 virus to prevent reinfection months later. The study found that 20-30% of infected people had declining virus neutralising activity despite having stable seropositivity six months later. The declining neutralising activity seen in 20-30% of infected people would … Continue reading COVID-19: Protection against reinfection may last only for months
Pre-existing memory T cells may reduce COVID-19 severity, but do not prevent infection
Pre-existing memory T cells that cross-react with SARS-CoV-2 may only reduce COVID-19 severity cannot prevent infection. The memory T cells are extremely unlikely to prevent SARS-CoV-2 infections. That is just not what T cells generally do. Hence, herd immunity cannot be achieved when only low percentage of the population is infected. At least five papers … Continue reading Pre-existing memory T cells may reduce COVID-19 severity, but do not prevent infection
SARS-CoV-2-specific T cell immunity prevents recurrent severe COVID-19 disease
The immune system elicits robust, broad and highly functional memory T cell responses once a person is infected with novel coronavirus. T cells were found even in the absence of detectable antibodies specific to SARS-CoV-2. This indicates a previously unanticipated degree of population-level immunity against COVID-19. Natural exposure or infection with the novel coronavirus may … Continue reading SARS-CoV-2-specific T cell immunity prevents recurrent severe COVID-19 disease
T cell memory that cross-reacts with novel coronavirus does not prevent infection, researcher clarifies
The presence of pre-existing T cell memory against four common cold coronaviruses which cross-reacts with novel coronavirus may not prevent SARS-CoV-2 infection, but at most be able to reduce the severity of COVID-19 disease and probably prevent people from dying. The T-cell memory does not allow populations to reach herd immunity when just 10-20% are … Continue reading T cell memory that cross-reacts with novel coronavirus does not prevent infection, researcher clarifies
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