• Are we spoilt for choice, or do we have a choice at all? 

By Dr. Dilshan Anthony Fernando   In the past few months, we have seen the emergence of several Covid-19 vaccines, and so much information is floating around that it may even be confusing as to which vaccine we are getting; what is covax; what is covishield; why are we getting a vaccine from India; and what is this one-shot Johnson & Johnson vaccine? With the hordes of information in circulation, it is natural for confusion to occur, so I will make an effort to try and simplify the matter. The Covid-19 vaccine available in Sri Lanka is the Oxford AstraZeneca vaccine, manufactured at the Serum Institute India, under the patronage of the COVAX alliance.   What is COVAX? COVAX is one of three pillars of the “Access to Covid-19 Tools (ACT)” accelerator, which was launched in April by the World Health Organisation (WHO), the European Commission, and France, in response to this pandemic. It brings together governments, global health organisations, manufacturers, scientists, private sector, civil society, and philanthropists with the aim of providing innovative and equitable access to Covid-19 diagnostics, treatments, and vaccines. The COVAX pillar is focussed on the latter. It is the only truly global solution to this pandemic, because it is the only effort to ensure that people in all corners of the world will get access to Covid-19 vaccines once they are available, regardless of their economic status.   Which vaccines are being distributed by COVAX? Currently the COVAX programme is rolling out the Oxford AstraZeneca vaccine, and also has come into terms with Pfizer BioNTech to distribute their vaccine equitably through the COVAX alliance as well.   Which vaccines are the forerunners in the global efforts to inoculate? The Oxford AstraZeneca, Pfizer BioNTech, Moderna, and the Jannsen vaccine by Johnson & Johnson seem to be the key players in the vaccination efforts at the moment. However, Sinopharm by China and Sputnik V by the Gamelaya Research Institute of Epidemiology and Microbiology in Russia are also in circulation, though information about the latter two are very limited.   Mechanism of action In comparison, the Oxford AstraZeneca vaccine and the Jannsen vaccine employ similar mechanisms of action. Both employ an adenoviral vector to deliver the Sars-coV-2 spike protein into human cells, which then trigger off an immune response, by which antibodies are developed, thereby giving immunity. The Oxford AstraZeneca vaccine uses an adenovirus from a chimpanzee.  The Pfizer and Moderna vaccines both employ similar technology, namely the mRNA (messenger RNA technology) in their vaccines. These vaccines introduce a specific genetic sequence into the body, by which they stimulate the human cells to produce an antigen, as opposed to the antibody development in AstraZeneca and Jannsen; however this antigen in turn stimulates antibody development in the Pfizer and Moderna vaccines. None of these vaccines actually inject you with the virus, contrary to popular belief.    Side effect profile  Thus far, none of the vaccines have shown any major side effects, other than severe allergic reactions, some reaching to the level of anaphylaxis (the most severe life threatening form of allergy). However, its long term effects are still being studied, as well as its effects on pregnant women and children; therefore those two categories are not being inoculated at the moment. The Oxford AstraZeneca vaccine mainly gives rise to fever, fatigues, body aches, and headaches, which may last for up to 72 hours, and can be managed with paracetamol and rest. The Pfizer BioNTech vaccine also gives rise to similar side effects, but it may also cause lymph node enlargement and temporary drooping of the face on one side, which may sound scary, but is a common side effect of some vaccines, and it is shortly reversed. The Jannsen and Moderna vaccines also show similar side effect profiles; however studies continue as to the long term effects of these vaccines.   How effective are these vaccines? Studies show that the Oxford AstraZeneca vaccine is 82.4% effective if given in two doses, three months apart. Studies on the Pfizer vaccine suggest that it is 52% effective after the first dose, and 95% effective after the second. The Janssen vaccine has proven to be 66 per cent effective in trials, according to the Belgian company, while studies on the Moderna vaccine show that it is 94% effective.  However, mere numbers shouldn’t mislead us into favouring one vaccine over the others, purely because development of immunity in response to a vaccine is a multifactorial process that may differ based on age, gender, race, etc. The Janssen vaccine, only requiring a single jab, appears to be favoured by many. However, how it achieves 66% effectiveness from one jab is not very clear.   Which ones are effective against the new variants? The University of Texas Medical Branch (UTMB) undertook research to find out the efficacy of the Pfizer Covid-19 vaccine, and the results were published in the New England Journal of Medicine. That research found that the level of neutralising antibodies developed in response to a person vaccinated with the Pfizer vaccine, if exposed to the South African variant, was two-thirds less. However, since there is no benchmark established in the level of antibodies that need to be maintained for the vaccines to be effective, further studies are ongoing. However, the authors of this research believe the Pfizer vaccine still remains effective against the South African variant as well. Moderna, another pharmaceutical giant who developed a Covid-19 vaccine, published its research in the New England Journal of Medicine, which reported a sixfold drop in antibodies against the South African variant. The Oxford AstraZeneca vaccine used in Sri Lanka and many other countries still appears to be effective against Covid-19. However, a study done in South Africa with 700 participants showed that the AstraZeneca vaccine is 54% less effective against the new South African variant, as opposed to other variants. Prof. Shabir Madhi, lead investigator on the AstraZeneca trial in South Africa, reports that the AstraZeneca vaccine is 89% effective in reducing severe manifestations of Covid-19. Oxford University Professor of Vaccinology Sarah Gilbert reported that efforts were underway to develop “booster” vaccines to improve the efficacy of the Oxford AstraZeneca vaccine against the new variants, and that these “tweaks” in the vaccines are easily made. The Jannsen vaccine appears to be the favoured vaccine against the South African variant, with 57% effectiveness. However, almost all the vaccines remain effective against the variants, and provide protection against serious illness and complications of Covid-19.     Storage Vaccines are made of volatile particles of protein, lipids, and other substances that are very sensitive to temperature. A minute temperature change can change the chemical structure of constituents of a vaccine, rendering it ineffective, and may require stocks of vaccines to be discarded as worthless. To put it in a layman’s context, it’s the same principle as storing food in a refrigerator to keep it longer from spoiling, because all chemical reactions slow down at lower temperatures. However, with vaccines, there are very specific temperatures and storage conditions that cannot be breached at any point from the manufacturing plant to the shipping containers, to transportation to storage facilities, and to the point of dispatch and vaccination. To put it in further perspective, the Pfizer-BioNTech vaccine needs to be stored at -70° Celsius, which is actually colder than the winter in Antarctica, while the Moderna vaccine has to be stored at -20° Celsius. These are ultra-cold temperatures which are usually not required in the current vaccines used, especially in Sri Lanka. In comparison, the Oxford AstraZeneca Vaccine can be stored at 2-8° Celsius (normal refrigerator temperature) for six months, and the Janssen vaccine can be stored at the same temperatures for three months, which makes it easier to distribute to rural areas without ultra-cold storage.   Do we have a choice of vaccine? In certain countries, you can pay and receive a vaccine of your choice. However, the vaccination drive in Sri Lanka is done totally free of charge, and therefore, Sri Lanka has thus far inoculated high-risk populations with the Oxford AstraZeneca vaccine – which according to all the information available is a world-class vaccine for all intents and purposes. Even though it comes under the label “Covishield” from Serum Institute India, it is the same Oxford AstraZeneca vaccine manufactured under the patronage of the COVAX alliance of the WHO. Therefore, unless you have life threatening allergies, or any other serious contraindications to the vaccine, let’s get inoculated in our efforts to defeat this pandemic, and let’s not allow misinformation and myths to guide us in this era of technology and knowledge.   (The writer is a medical officer currently attached to a government hospital. His experience spans across the medical profession as a medical practitioner, and across the pharmaceutical and surgical equipment industry. He also possesses an MBA and a Diploma in Economics. Having represented his university rugby team in international tournaments, he also has a special interest in sports medicine)