![]() ![]() Finally, some experts have warned that partial vaccination leading to a less robust immune response may increase the risk of mutations, which, as we’ve seen, can lead to variants with more problematic characteristics. The probability of this is hard to quantify, though it can most likely be addressed with a strong messaging campaign. It is possible that some people will be confused by a change in the vaccine schedule, and the confusion may lead them to eschew vaccination altogether or believe that they need only a single dose. 7 Some people may forget to return for their second dose after a longer delay, though a reminder system that works for a return in 3 to 4 weeks should work a month or two later. 6 Immunity may begin to wane between the first dose and a delayed second dose, although the rarity of recurrent infections probably means that immunity, at least that created by native infection, lasts for much longer than 3 months. It is possible that the second dose will be less effective when given later, though few scientists believe this will be the case. 5 This prospect further increases the imperative to vaccinate the population, particularly people at high risk, more quickly.Īre there potential risks from delaying the second dose? Sure. 4 This variant rapidly became the dominant strain in much of England, and the Centers for Disease Control and Prevention (CDC) now predicts the same for the United States in the next 6 weeks. variant) that is approximately 50% more infectious than the native coronavirus. Second, we have recently seen the emergence of several viral variants, with one (B.1.1.7, often referred to as the U.K. ![]() Why consider delaying the second vaccine dose? First, with Covid-19 currently killing approximately 3000 people in the United States per day, we face a crucial tradeoff: do we use our limited vaccination capacity to increase the protection of persons who have received a first dose from approximately 85% (after dose one) to 95% (after dose two) by administering a second dose? Or do we use that same capacity to take a similar number of people from an unprotected state to one in which they are 80 to 90% protected? One model shows that the expected number of Covid-19 cases would be significantly lower if more people were given a first dose, even if it came at the cost of deferring the second doses. ![]() By the day of the injection of the second dose, the efficacy of the first dose was somewhere in the range of 80 to 90%. In both trials, the cases in the placebo and active vaccine groups began to diverge about 10 days after the first dose, with growing vaccine efficacy over time. But the argument is based on an overly narrow definition of science. Some argue that any deviation from the protocol used in the clinical trials is unscientific. This may be a case in which the risks of strict adherence to the plan outweigh the risks of modifying it. However, the current circumstances - a slow vaccine rollout, a limited vaccine supply, and the recent emergence of more infectious SARS-CoV-2 variants that threaten to outpace our vaccination program - are anything but normal. Under normal circumstances, the vaccines should be deployed in keeping with the trial protocols. Both vaccines had approximately 95% efficacy after the second dose - an impressive finding. The clinical trials of the Pfizer–BioNTech and Moderna vaccines involved two injections given 3 to 4 weeks apart. The most trusted, influential source of new medical knowledge and clinical best practices in the world. Information and tools for librarians about site license offerings. Valuable tools for building a rewarding career in health care. The authorized source of trusted medical research and education for the Chinese-language medical community. The most advanced way to teach, practice, and assess clinical reasoning skills. Information, resources, and support needed to approach rotations - and life as a resident. The most effective and engaging way for clinicians to learn, improve their practice, and prepare for board exams. NEW! Peer-reviewed journal featuring in-depth articles to accelerate the transformation of health care delivery.Ĭoncise summaries and expert physician commentary that busy clinicians need to enhance patient care. NEW! A digital journal for innovative original research and fresh, bold ideas in clinical trial design and clinical decision-making.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |