The news of various vaccines with different efficacy levels has lifted the hopes of many. However, there are many unanswered questions about them such as are they safe, can they be used on children, when will the vaccination start and how long can the effectiveness last. Also, supplies of the vaccines would initially be prioritised with health workers, older people and other at-risk populations getting them first. DR KAFEEL KHAN says it could take several years for the vaccine to reach the last person so it is best to continue using masks and sanitisers and ensure social distancing..—————-.As coronavirus cases surge around the world, hospitals are getting overstretched and economies, gasping. Within a week, there was good news from two US-based companies and both were to do with the much-awaited vaccine that spells hope in these dire times. .The first was Pfizer (and its partner German company BioNTech), which announced on November 9, 2020, that their mRNA-based vaccine against Covid-19 had more than 90% effectiveness and the second was on November 16 when Moderna claimed that its mRNA-based vaccine appeared to be 94.5% effective..What are the efficacy levels?.So what does this mean to ordinary people? .The US-based Food and Drug Administration had set a bar of 50% efficacy for a vaccine–it's far more protective than that with a claim of more than 90% effectiveness. Currently, more than 150 coronavirus vaccines are in development across the globe, out of which 11 have reached Phase III trials. The promising ones are from Moderna, Pfizer and BioNTech, Johnson & Johnson, India's Bharat Biotech and ICMR, UK's Novavax, AstraZeneca-Oxford and China's Sinopharm and CanSino. .“So what is a vaccine? A vaccine uses the body's natural defences to build resistance to specific infections by training the immune system to create antibodies, just as it does when it's exposed to a disease. However, because vaccines contain only killed or weakened forms of germs, they do not cause the disease or put one at risk of its complications. The immune system remembers the disease and if a vaccinated person is exposed to the germ in future, it can quickly destroy it before the person becomes unwell..To date, just two coronavirus vaccines have been approved, both by Russia. These are Sputnik V and EpiVacCorona, but experts have raised considerable concern about their safety and efficacy. However, the fact that Pfizer and Moderna have got encouraging results is making experts optimistic about them..So what is a vaccine? .A vaccine uses the body's natural defences to build resistance to specific infections by training the immune system to create antibodies, just as it does when it's exposed to a disease. However, because vaccines contain only killed or weakened forms of germs, they do not cause the disease or put one at risk of its complications. The immune system remembers the disease and if a vaccinated person is exposed to the germ in future, it can quickly destroy it before the person becomes unwell..Both Moderna's and the Pfizer-BioNTech's vaccines are mRNA vaccines, a new technology where the vaccine contains a piece of genetic code that trains the immune system to recognise the spiked protein on the surface of the virus..Any vaccine development has to go through different phases. This usually takes years, but due to COVID-19's enormous ill-effects on health, the social-regulatory framework has been relaxed. .The norms for vaccine trials are as follows: .1-Preclinical 4-Phase-3(efficiency trials)2-Phase-1(safety trials)5-Regulatory Review3-Phase-2 (expanded trials)6-Approved and distributed.How a vaccine works.Is all news good?.However, I am still sceptical about the news of these vaccines and their efficacy for many reasons. .*Are they safe?–Although both companies announced that no serious safety concerns were observed in any of the participants during Phase III trials, barring minor side-effects such as fatigue, muscle aches and pain at the injection site, clinical trial/safety and additional efficacy data continue to be collected. The participants will continue to be monitored for long-term protection and safety for an additional two years after their second dose and then only can it be determined if millions should get it..AstraZeneca had to halt its Phase III trial in September 2020 twice as some participants developed neurological symptoms. Recently, China's Sinovac too had to stop its trial as one participant died..“Although both companies announced that no serious safety concerns were observed in any of the participants during Phase III trials, barring minor side-effects such as fatigue, muscle aches and pain at the injection site, clinical trial/safety and additional efficacy data continue to be collected. The participants will continue to be monitored for long-term protection and safety for an additional two years after their second dose and then only can it be determined if millions should get it..The data is still preliminary and taken only after seven days of the second dose. Both require people to get two shots, 3-4 weeks apart. It could be years before it is known how long a coronavirus vaccine remains effective. This means that annual boosters could be a feature of future life, like the flu vaccine..*"Infantry wins battles but logistics wins wars"—The mRNA-based vaccines need to be stored at a very cold temperature. Both the Moderna and Pfizer vaccines are frozen, but at different temperatures. Pfizer's vaccine needs to be stored at temperatures matching an Antarctic winter – a logistical nightmare, especially in places like India where there are heat waves exceeding 50º C. Scarce ultra-cold freezers, poor electric supply and a largely rural population make this a difficult proposition. We might be successful in cities though. Pfizer has announced that it will provide a "dry ice pack" container for its vaccines which can maintain a temperature of -70º C for up to 10 days. Moderna is claiming a longer shelf life of 30 days at refrigerated temperature, but it's not for the rural Indian set-up. The success of any Covid-19 vaccination programme will critically depend on the robustness of the cold chain..* Will it work on children? — The answer is no. Both trials have been done only on adults..* When will this vaccination start?–Both will likely apply for emergency use authorisation in the coming weeks after more safety data is collected. After that, it may take weeks to know about the vaccine's safety, effectiveness and the companies' ability to safely manufacture them. The vaccine could be authorised for certain high-risk populations by early next year, but that would only happen if everything goes as planned and there are no unforeseen delays..*Does it mean we have won the battle against coronavirus?—The impact of the vaccines on the pandemic will depend on several factors such as their effectiveness, how quickly they are approved, manufactured and delivered and how many people get vaccinated. It's going to require a humungous amount of vaccines to meet the global demand and for use across a range of populations and settings..A vaccine will supplement other treatment."A vaccine will complement the other tools we have, not replace them," WHO director-general Tedros Adhanom Ghebreyesus reportedly said. "A vaccine on its own will not end the pandemic." Development of new technologies, even during a global crisis, does not automatically mean access; developing countries like India may have to wait a little longer..“The impact of the vaccines on the pandemic will depend on several factors such as their effectiveness, how quickly they are approved, manufactured and delivered and how many people get vaccinated. It's going to require a humongous amount of vaccines to meet the global demand and for use across a range of populations and settings..Supplies of the vaccine would initially be prioritised with health workers, older people and other at-risk populations getting them first. It could take several years to reach the last person. The vaccine will not save the world in the coming months when the virus will take many more lives unless the government takes more stringent public health measures..Contact tracing, testing more and more people, isolation and quarantine will need to continue. This, along with social distancing norms, mask wearing and hand hygiene practices could stem the deadly march of this virus somewhat. .(Dr Kafeel Khan is an Assistant Professor in the Dept of Paediatrics at BRD Medical College, Gorakhpur, Uttar Pradesh. The views are personal.)
