The surprising efficacy rates of vaccines
IE quoted leading medical scientist in India Dr Gagandeep Kang as saying that the 90% efficacy rates of several vaccines was very surprising because in cases of mucosal infections there is less protection than in infections at other sites. Dr Kang gave the example of influenza vaccines which offer about 60% efficacy in a good season, with this figure going much lower in cases where strains do not match. This is why the scientists were not expecting the vaccines to perform as well as they have as per the early data. The doctor further stated that further trials and analysis into these vaccines would reveal that these efficacy levels would not be maintained. However, the medical scientist also assured that for the reasonable timeframe, the rates are not going to decline drastically.
Which vaccine is better suited for India?
Vaccine developed by Pfizer and BioNTech is not feasible for developing countries like India due to the requirement of a sub-zero ultracold storage facility. Hence it is important to look at vaccines that would be more suitable to the infrastructure facilities available in the country.
Apart from that, Dr Kang stated that it is important that the vaccine is affordable, can be manufactured in large numbers and is easily deliverable, as a single dose preferably. Moreover, the vaccine should provide long-term protection.
Dr Kang also explained that the current immunisation programme in the country does not have a vaccine as expensive as the one developed by Oxford-AstraZeneca, which is priced at $3 a dose, the lowest of all announced COVID-19 vaccines. Two doses of the vaccine would be needed, making it $6 a person just for the doses, and this amount will go to about $10 a person per set of vaccination in the campaign mode. With this, the vaccine would become the most expensive one the country has seen even at an individual cost level, let alone in terms of the number of people that would need to be vaccinated.
The doctor advised that for a national immunisation drive to vaccinate everyone in the country, India would need a vaccine costing less than a dollar, or preferably, less than 50 cents a dose, and hence, this should be the aim of candidates in the second wave of vaccine development.
How soon will vaccine become available in India?
Dr Kang said that among the first-wave vaccines developed in the country, the first ones to come out would probably be the two mRNA candidates, developed by Pfizer-BioNTech and Moderna, and the one by AstraZeneca.
She, however, stated that the initial availability of the vaccines would be limited and the situation would get better with the increase of production. The doctor added that the country is not likely to have a serious amount of vaccine doses for another three to five months, even with successful candidates.
What things lean in favour of AstraZeneca candidate?
An IE report stated that the vaccine candidate developed by Oxford-AstraZeneca was found to be 90% effective when participants were administered a lower dose first and then given a full second dose at least a month later. On the other hand, two full doses of the vaccine administered at least a month apart led to a drop in the efficacy to 62%.
This means that by administering low dosage, the country can achieve a higher percentage of protection, while also leading to more people receiving vaccine dosage in the same limited supply due to the lower requirement per person. This can be particularly favourable for governments of countries like India which need to immunise a large population.
The status of Oxford-AstraZeneca vaccine in India
The Serum Institute of India (SII), Pune, is carrying out Phase 3 trials for the AstraZeneca vaccine in India with about 1,600 participants, to study the vaccine candidate’s safety and efficacy among Indian population. Experts believe that data from this study, coupled with the results released by AstraZeneca from its global study, could help SII get faster approval for the vaccine, dubbed Covishield in India, from the regulatory authorities.
Efficacy and cost of several candidates
Pfizer-BioNTech have said that their mRNA-based vaccine had an efficacy rate of 95%. While the results are encouraging, the fact that the vaccine requires nearly cryogenic cold storage facility can make it infeasible for countries like India. Moreover, while the price of the vaccine is yet to be announced, it is estimated to cost over $19 per dose.
Another mRNA-based vaccine developed by Moderna was announced to have an efficacy of 94.5%. This vaccine requires to be stored at -20 degrees Celsius, but can also be stored at temperatures of around 2 degrees Celsius to 8 degrees Celsius for a month, the report said. However, the vaccine is not suitable for countries like India, since it would cost between $25 to $37 a dose for different governments.
Sputnik-V by Russia is based on non-replicating viral vector. The vaccine is said to be 92% effective, and needs to be stored at 18 degrees Celsius in liquid form, and between 2 degrees and 8 degrees Celsius in freeze-dried form, which would make it suitable for India’s infrastructure and logistics facilities. While the official prize of the vaccine has not been released, it is expected to be significantly cheaper than Moderna and Pfizer candidates.
Lastly, Covishield can also be stored between 2 degrees and 8 degrees Celsius, and it would cost about $3 a dose for the government. This price would go up to nearly $7 to $8 for the masses.