Tuesday, September 27, 2022

India to start Covid mix-and-match booster vaccines

India said on Wednesday that Biological E’s Covid-19 vaccine Corbevax can be administered as a booster dose in people who have taken the country’s other two main shots, Covaxin and AstraZeneca’s Covishield, from Friday.
Corbevax will be available to over 18s as precautionary booster six months after a second dose, the health ministry said in an August 8 letter to state authorities and shared with reporters on Wednesday.
New test can tell how much immunity you have: Meanwhile, researchers in the US have developed an easy-to-use test that can predict the degree of immune protection people have against COVID-19, either from vaccination, infection, or a combination of the two.
Easy access to this kind of test could help people determine what kind of precautions they should take against COVID-19 infection, such as getting an additional booster shot, the researchers said.
Described in the journal Cell Reports Methods, the test measures the level of neutralising antibodies — responsible for defending cells from the virus — that target SARS-CoV-2 in a blood sample.
“Among the general population, many people probably want to know how well protected they are,” said Hojun Li from Massachusetts Institute of Technology (MIT)’s Koch Institute for Integrative Cancer Research, US.
Li and his collaborates developed a device that can detect the presence of antibodies that block the SARS-CoV-2 receptor binding domain (RBD) from binding to ACE2, the human receptor that the virus uses to infect cells.
The first step in the test is to mix human blood samples with viral RBD protein that has been labelled with tiny gold particles which can be visualised when bound to a paper strip.
After allowing time for antibodies in the sample to interact with the viral protein, a few drops of the sample are placed on a test strip embedded with two test lines.
One of these lines attracts free viral RBD proteins, while the other attracts any RBD that has been captured by neutralising antibodies, the researchers said.
A strong signal from the second line indicates a high level of neutralising antibodies in the sample, they said.