A UK-based study has shown that a longer break between two doses of COVID19 shot developed by Pfizer-BioNTech might result in higher overall levels of antibodies as compared to a shorter gap. However, antibody levels do not sustain for long after the first dose of the shot. The study has been led by experts from Oxford University. The findings of the study will help improve inoculation policies against the Delta variant that reduces the efficiency of the first dose of the shot even though two doses of the vaccine are considered highly effective. The Delta variant has been categorized as the variant of concern. One of the authors of the study has said that the eight-week gap between the two doses of the shot is a sweet spot against the concerning strain. Dr. Susanna Dunachie who is a professor of Infectious Disease at the University of Oxford has said that on average shorter dosing gap has led to lower levels of antibodies. Dr. Susanna Dunachie is the joint chief investigator of the study. Dr. Dunachie has said that a longer gap can lead to higher levels of antibodies at a population level although two doses of the shot are very effective in inducing a robust immune response. Even if people have taken two doses on a shorter dosing gap, they do not need to worry; it is a great vaccine against COVID19. The UK-based study has enrolled 503 health care workers. The authors of the study have said that either dosing plan has led to a robust antibody and T cells response among participants.
The authors of the study have claimed that when the shot has been given at a longer gap, poor levels of neutralizing antibodies have been seen after the first shot against the Delta strain. Participants have not been able to maintain the levels of neutralizing antibodies during the gap prior to the second dose. However, after two doses of the shot, the levels of neutralizing antibodies have shot up by twofold after the longer dosing gap as compared to the shorter dosing gap. Neutralizing antibodies are considered to play a vital role in protection against the SARS-CoV-2 virus. Nevertheless, it is not a complete picture as T cells as well play a crucial role in preventing the virus. Apart from T cells and neutralizing antibodies, B cells or memory cells are one of the tools of the immune system as well. Health experts have seen that overall levels of T cells have been 1.6 times lower when the shot has been given on a longer dosing gap as compared to the shorter dosing interval of 3 to 4 weeks. However, with the long gap, the proportion of T cells have been high that helps in long-term immune memory. The former chairperson of the British Medical Association (BMA) Public Health medicine Committee, Dr. Peter English has said that experts often tend to stress neutralizing antibodies as a measure of the immune response but cellular immunity as well as a very essential part of immunity that is hard to measure. The findings of the study have been released as a preprint. The authors of the study have said that a second dose is essential for full protection against the Delta strain; however, halting the second dose will lead to the protection that is more durable even if it is at the cost of immunity in the short term.
The lead author of the study Dr. Susanna Dunachie has said that it appears that the UK strategy to go ahead with a longer dosing schedule has been productive. The longer dosing plan adapted by the UK has been based on the knowledge of shots for other ailments. The longer dosing plan is often better as it helps in vaccinating as many people as possible with one dose of the shot. Experts have said that a longer dosing schedule has resulted in offering higher levels of antibodies. In December 2020, the UK government has increased the gap between two doses of Pfizer shot by 12 weeks. However, Pfizer has cautioned the UK government that there is no evidence to support the decision of holding up the second dose. Health officials from the UK government have advised that health care should vaccinate people in an eight-week interval between two doses of the shot that will offer higher immunity against the Delta variant more rapidly. An eight-week dosing schedule will elevate immune response in long term as well. The Delta variant that has been termed as one of the variants of concern by the World Health Organization (WHO) has been tagged as one of the most contagious strains. The variant has been circulating across many states in the US. The Delta strain has been causing a surge in cases of COVID19 once again.