6 minutes agoAuthor: Ravindra Bhajani

The results of a new study in the United Kingdom (UK) have come out. Scientists at the Institute of Health Informatics, University College London, found that after 10 weeks the vaccine started reducing antibodies made against Kovid-19. This raises many questions. After all, how long will the vaccine keep from Kovid-19? Is this happening with all vaccines? After the results of this study, will there really be a need to take a booster dose now? Let us understand sequentially….

What does the new study in the UK say?

  • A Virus Watch study by University College London (UCL) has found that antibodies made from vaccines from Pfizer and AstraZeneca begin to decline after six weeks. After 10 weeks it was only 50%.
  • The UCL team has analyzed blood samples of 605 vaccinated people aged 50-70 years. They found that antibody levels were different in all individuals. But Pfizer’s vaccine produced more antibodies than AstraZeneca’s vaccine.
  • The antibody level was 7,500 units per ml six weeks after the second dose of Pfizer’s vaccine, but dropped to 3,320 after 10 weeks. At the same time, antibody levels from the AstraZeneca vaccine dropped from 1,200 units per ml to 190 units per ml in 10 weeks. In the results published in The Lancet, researchers have claimed that they have seen such a trend in a study done on 4,500 participants.

What is the significance of decreasing antibody levels in the fight against COVID-19?

  • Scientists say that there is no need to worry about the drop in antibody levels after a few weeks of vaccination. But researchers say that somewhere it can reduce the effectiveness of the vaccine. It also does not mean that people are falling prey to breakthrough infection because of this. Breakthrough infection means getting infected with Kovid-19 despite vaccination.
  • Antibody levels are important in protection against Kovid-19, but the immune system has other weapons to fight infection. Memory B cells remember the virus and when an infection occurs, they immediately start making antibodies. Tea killer cells target and kill infected cells, which provide an extra shield of protection.
  • Dr. Chandrakant Laharia, an expert in epidemic related matters in India, says that it would not be right to consider only antibody levels as protection. We get protection at many levels and for how long it will be available, more study is needed about this.

So might a booster dose be needed?

  • Yes. Researchers have investigated the effectiveness of the vaccines of Pfizer and AstraZeneca. He says the study results suggest that those who were initially vaccinated and those who received the AstraZeneca vaccine should be given a booster dose after a few months.
  • Professor Rob Aldridge at University College London has said that we know that antibodies are initially high and after some time they become low. We are concerned that if antibody levels continue to drop at this rate, the protection of the vaccine will also start to decline. The big question for us is when will this happen?
  • Aldridge says that antibodies are not the perfect way to measure risk. We don’t know what the magic number is when the risk of infection or hospitalization will be low. It is necessary to find out this magic number.

What is happening in different countries regarding booster doses?

  • Pfizer had talked about the need for a booster i.e. the third dose after the breakthrough infection came to the fore. After this, many countries including Israel have started applying booster doses to the high risk group i.e. people facing some kind of serious disease.
  • The delta variant is also a rationale behind the need for a booster dose. This variant is currently active in over 125 countries. In India, 86% of the new cases are of the delta variant. Breakthrough infections have also come up here, on which the Indian Council of Medical Research (ICMR) has also studied.
  • The US has said that people may need a booster dose, but more research is being done in this regard. The mix and match strategy of the vaccine is also being considered. A decision on this will be taken only after the results of the research.
  • The World Health Organization (WHO) has said that there is no scientific confirmation that a booster dose of the vaccine is necessary. The organization has also said that instead of giving booster dose of vaccine to developed countries, vaccine should be given to such countries where there is a shortage of vaccine.
  • India’s target is to vaccinate maximum of its population first. Only after that, based on the results of the research, a decision will be taken on the booster dose of the vaccine as per the requirement.

Is the vaccine not effective against different variants?

  • The vaccine is making antibodies against all the variants. A study conducted in the UK on the effectiveness of Pfizer and Moderna vaccines has revealed that both doses of Pfizer are 96% effective in protecting a person infected with the delta variant from hospitalization.
  • Bharat Biotech has reported 65% efficacy of the vaccine against the delta variant in the Phase-3 trial data of Covaxin. The Russian vaccine Sputnik V is also 90% effective against the delta variant. However, Sputnik was 92% effective on the original virus.
  • The effectiveness of the Chinese vaccine Sinovac against the delta variant has decreased. After this, Thailand has announced that a third dose of AstraZeneca will be given to health workers taking the Chinese vaccine. The Gulf countries had also got the Chinese vaccine and if the case increases there, the third dose of Pfizer is being applied as a booster dose.

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