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
Neutralizing antibodies
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
Study finds Covishield produces more antibodies than Covaxin, but scientists point out serious flaws with the preprint
A head-to-head evaluation of immune responses to spike protein after the first and second dose of Covishield and Covaxin in 515 health-care workers show that both vaccines elicited good immune responses after two doses. Higher seropositivity rate and higher median antibody titer values are seen for Covishield compared with Covaxin. However, the preprint has several … Continue reading Study finds Covishield produces more antibodies than Covaxin, but scientists point out serious flaws with the preprint
Covaxin offers protection against double mutant (B.1.617) variant
A study has found that people who have been vaccinated with Covaxin have protection against the double mutant (B.1.617) variant first found in India. The ability of the sera of vaccinated people to neutralise the B.1.617 variant was found to be two-fold less. A study has found that people who have been vaccinated with Covaxin … Continue reading Covaxin offers protection against double mutant (B.1.617) variant
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
Moderna, Pfizer vaccines neutralise variants encoding mutations E484K or N501Y but with less potency
The neutralisation by 14 of the 17 most potent antibodies was reduced or abolished by either K417N, or E484K, or N501Y mutations in sera of people vaccinated with Moderna or Pfizer vaccine. In a small cohort involving just 20 trial participants, researchers have found that both Moderna and Pfizer-BioNTech are able to neutralise SARS-CoV-2 variants … Continue reading Moderna, Pfizer vaccines neutralise variants encoding mutations E484K or N501Y but with less potency
Oxford vaccine found safe and immunogenic even in older adults
Results of the Phase-2 trial of the Oxford vaccine show that the vaccine is safe across age groups — younger (18-55 years age) and older adults (over 56 years age). In fact, older adults better tolerated the vaccine than younger adults, the results show. The vaccine also induced T cell immune responses and neutralising antibodies … Continue reading Oxford vaccine found safe and immunogenic even in older adults
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
A case of coronavirus reinfection in Hong Kong confirmed by genome sequencing
Using genome sequencing, researchers at the University of Hong Kong have found a rare instance of reinfection with novel coronavirus for the second time, four-and-a-half months after the first infection. The first viral genome belongs to GISAID clade V, while the second genome belongs to GISAID clade G. Using genome sequencing, researchers at the University … Continue reading A case of coronavirus reinfection in Hong Kong confirmed by genome sequencing
Intranasal vaccination of a coronavirus candidate vaccine prevents infection
A new vaccine candidate construct using chimpanzee adenovirus carrying the full length of novel coronavirus spike protein is able to achieve sterilizing immunity and prevent both upper and lower respiratory tract infection in mice when administered intranasally but not when given via the intramuscular route. A new vaccine candidate construct using chimpanzee adenovirus carrying the … Continue reading Intranasal vaccination of a coronavirus candidate vaccine prevents infection
Science Chronicle 