CME INDIA Presentation by Admin.
THE LANCET has published a Research Paper according to which, if COVISHIELD is administered 12 weeks or 3 months after the FIRST dose, it gives the best possible results so far as the Prevention from Reinfection is concerned and it gives the best immunogenic response. Now what are we waiting for? – Dr Pramod Mathur, Alwar, Rajasthan.
This vital issue addresses the approach to a critical policy failure. Is it the Yaksha Prashna in Covidology today or not? No, it is not. As science is able to answer the question but issues are twisted. Yaksha Prashna ,यक्ष प्रश्न, also known as the Dharma Baka Upakhyana or the Akshardhama, is the story of a question-and-answer dialogue between Yudhishthira and a yaksha in the Hindu epic Mahabharata.
Questions that haunt
- Why 2 doses?
- Do you recommend delaying the second dose or following the standard regimen?
- Are 2 doses enough to increase the immunity sufficiently?
- What is the best time of having the 2nd dose and is a booster dose again required after the 2nd dose?
- The clinical trials of the Pfizer–BioNTech and Moderna vaccines involved two injections given 3 to 4 weeks apart.
- Both vaccines had approximately 95% efficacy after the second dose — an impressive finding.
- But the current circumstances — a slow vaccine rollout, a limited vaccine supply, and the recent emergence of more infectious SARS-CoV-2 variants have threatened to outpace vaccination program in many countries.
- 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.
- When the COVID 19 vaccines were first tested the first dose gave rise to a relatively low level of immunity in a few weeks. This was substantially strengthened by a 2nd dose.
- This led to the 2nd dose becoming a part of the protocol by the researchers. The trials therefore started to look at the immunity conferred after the 2nd dose of vaccine which was administered after 3 to 4 weeks. The results showed very convincingly that the immunity was strong enough to prevent symptomatic COVID 19 infections.
- However, since the trials were giving 2 doses, it is hard to comment on how much immunity was conferred by the single dose alone.
- Many people are sceptical of vaccines, fearing that the speed of development has necessitated cutting corners.
- Policy makers think that suddenly changing dosing recommendations puts public confidence at serious risk and will impede willingness to be vaccinated at all.
Story suddenly chanced
- Lancet published data from three single-blind randomised controlled trials online on 19th Feb 2021.
- The results of this primary analysis of two doses of ChAdOx1 nCoV-19 are consistent with those seen in the interim analysis of the trials and confirm that the vaccine is efficacious, with results varying by dose interval in exploratory analyses.
- The study conclusion clearly states that a 3-month dose interval might have advantages over a programme with a short dose interval for roll-out of a pandemic vaccine to protect the largest number of individuals in the population as early as possible when supplies are scarce, while also improving protection after receiving a second dose.
- The new data from United Kingdom, the country of origin of the Oxford vaccine, now suggests that the dosage interval of 12 weeks should be preferred. The researchers found vaccine efficacy reached 82.4% after a second dose in those with a dosing interval of 12 weeks or more. If the two doses were given less than six weeks apart the efficacy was only 54.9%.
Now the evidence is strong
- The 12-week gap between first and second dose seems to be a better strategy as more people can be protected quickly and the ultimate protective effect is greater.
Dr A K Singh, Endo, Kolkata tweets
Dr Suresh Kumar, Infectious disease consultant, Apollo Hospital, Chennai shares:
Dr Keyur Achyra, Intensivist, UK shares:
- Another very encouraging ” real life” outcomes from Israel. 500,000 (yes, half millions) people being followed for infections over 24 days after a single Pfizer dose.
- Days 0 to 8 after vaccine – cases doubled mostly due to behaviour changes.
- Day 0 to 14 – vaccine efficacy almost zero!
- Days 8 to 21 – cases going down.
- At day 21- vaccine efficacy 91%.
- It is unlikely that immunity will suddenly come down after 3 weeks. Going by natural infections course, it will level off gradually.
What About New Variants?
- The data suggests that the new variants seem to increase the ability of COVID-19 to spread but do not influence the degree of sickness. The current vaccines appear to work against the new variants.
- When vaccines are created, they are designed to create different antibodies to various components of the virus.
Still Policy makers continue with old Schedule
- The logic given by many policy makers is that decisions have to be data-driven and that each country, depending on the data that it collects on the efficacy of the vaccine, take a decision that is best suited for that country. This seems to be very vague.
CME INDIA Learning Points
- There is a big mistrust between the scientific data and Indian policy makers.
- Vaccination Hesitancy is emerging as a major problem.
- In spite of recent surge of new infections at some places in India, people are not interested in getting vaccinated.
- Some physicians plan to defer the 2nd dose of vaccine by 8 to 12 weeks.
- Many are very scared to defer it only due to fear that they might not get the 2nd dose and vaccination certificate.
- There is no scientific data supporting the 28 days schedule of 2nd dose.
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