UPDATE ON COVID 19 VACCINES:

Vaccination drive commendable, but don’t lower guard

BY Dr. H. T, Wickremasinghe
Senior Consultant Paediatrician
President, Vaccine and Infectious Diseases Forum of Sri Lanka

It is commendable that the government of Sri Lanka has planned to get down 9 million doses of Covishield Vaccine from Serum Institute of India, the world’s largest vaccine manufacturing company. This vaccine is actually none other than AstraZeneca –Oxford Vaccine manufactured by The Serum Institute of India, by the name of Covishield. To date, Sri Lanka has already administered about 200,000 doses to healthcare workers. The next consignment would be given to persons over 65 years and persons with comorbid conditions such as diabetes, hypertension, heart disease and kidney disease.

With the rolling out of the vaccine globally, new observations have surfaced. The original schedule of the vaccine was to give two doses 28 days apart. This provided almost 70% immunity. However, new evidence has come out last month, suggesting that it would be better to increase the gap between two doses to 12 weeks (three months) instead of four weeks. This would offer a more robust 84% immunity. The United Kingdom is already using the 3 months interval between two doses. This will provide greater flexibility for vaccine rollout, and help the health authorities to deal with any possible supply disruptions, while consistently sustaining the maximum immunity to the public.

A study done by the independent COVID-19 Vaccine Research Group in the UK had shown that until the time of conclusion of the study at three months, a single standard dose would provide 76% protection with no declining of immunity. How long this protection would last is not known yet. But time would tell us. As with any other vaccine, an introduction of a second dose at three months would certainly boost the immunity.

The second observation made during the roll out of this vaccine is that it appears to provide some form of protection to community spread of the disease. This study revealed that there was 67% reduction in community spread of the disease. This is in fact very good news, as when we go on vaccinating more and more people, there would be less and less community spread of the disease, reducing the burden on hospital medical services.

Another issue which surfaced while rolling out of the vaccine is the safety and efficacy of the vaccine in persons over 65 years of age. Unfortunately, all phase 3 trials done by AstraZeneca have not included many persons over 65 years of age. They primarily targeted the 18-55 year age group. According to the data from AstraZeneca’s phase 3 trials, only two out of 660 persons in the trial aged over 65 were infected with COVID-19. Such a small number of participants is grossly insufficient to make a global decision. It is obvious that AstraZeneca has failed to provide reasonable data of safety and efficacy of their vaccine in the elderly population. They are already paying the penalty as countries such as Germany, France, Austria, and South Africa have declined to use the vaccine for persons over 65 years, despite the recommendation made by the European Medicines Agency (The governing body of drug evaluation in EU countries) to use the vaccine for all ages. However, the United Kingdom decided to continue vaccination for all ages, including persons of over 80. Their interim analysis during the early part of the vaccination programme shows that the vaccine is not only effective and provide the same immunity as for others but also has slightly less side effects.

Considering the seriousness of COVID 19 in the elderly and it’s very high mortality, it is my considered opinion that even if the vaccine is less effective or has more side effects, it is still worth giving it to old persons as it would save their lives.

With more and more new genetic variations of SARS CoV 2 virus emerging, a reasonable concern has transpired among scientists whether the vaccines would be able to provide immunity to the new emerging strains. Up to now globally there are more than 8000 variants. Out of those, three variants, the South African variant, the Kent (UK) variant and the Brazilian variant are few rapidly gaining global spread. The UK variant has been identified in Colombo, Avissawella, Biyagama and Vuvuniya.

Studies done in UK has shown that AstraZeneca vaccine would provide immunity to the UK variant. However, a similar study done on over 2000 participants in South Africa has unfortunately revealed that this vaccine is not effective against the new South African strain.

There are more than 150 vaccines against COVID 19 in the production pipeline. Out of those, a dozen are nearing completion and awaiting submission of their dossiers to the World Health Organization for approval. With such a vast array of vaccines, it would be easy for WHO to distribute vaccines early to provide vaccination to all needy people in the world. But it would not be easy to have the same vaccine supply without disruptions with the expanding global demand. At the same time, some vaccines would show immunity to some new emerging variants, while another vaccine would show immunity to other variants. This brings us to another new strategy. What if we combine vaccines? Combined vaccines theoretically will provide greater flexibility for vaccine rollout and help to deal with any possible intermittent supply shortages of a particular brand.

However, the official guidance given by vaccine authorities in the world state that anyone who has already taken a vaccine should get the same brand of vaccine for both doses. The US Food and Drug Administration and the UK’s Joint Committee on Vaccination and Immunization (JCVI) recommend as much. It’s only in ‘very rare circumstances’ that vaccines of different brands may be used and only if one vaccine is available at a certain time, or it is not known which one was administered for the first dose. Nevertheless, the usefulness of a combined vaccine, in case of a short supply or with combating a new emergent variant, cannot be underestimated. New research is underway to find out the efficacy and safety of such combinations. The initial report with AstraZeneca-Pfizer vaccine combination will be available by mid-2021. Similar trials will be undertaken soon, so that the health authorities of countries would have a better and competitive option of choosing vaccines for their public.

Despite all this good news, we still have a question for which we have to wait for an answer. How long the immunity will last is the question for with no answers are available yet. Many countries have already commenced their vaccination programme, even before the introduction of the free vaccine programme by WHO sponsored COVAX. In the race of COVID-19 mass vaccination, Israel is well ahead of all the countries in the world already covering 43% of the total population. The number of new cases and deaths due to COVID-19 has come down. Even in the US, the initial wave of vaccination is slowly showing results of reduction of mortality from COVID-19 related complications.

The majority of the vaccines used so far may not provide the expected picture-perfect immunity and the world may continue to have COVID 19 infections, but based on evidence, speculations have already been made to claim that vaccination could provide almost 100% protection from death. This is what we all want.

With that positive note, let me conclude while emphasizing the need to continue our general public health measures such as wearing masks, social distancing and avoiding crowded gatherings to reduce the risk of contact with an infected person.

There is no science to beat common sense.