How the pandemic will play out in the next few years will depend on vaccines — their availability, coverage and duration of protection.

This article is part of the series — The Future of the Pandemic in 2021 and Beyond.

As 2020 comes to a close, there are a projected 83 million confirmed cases of Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV2) and about 1.8 million deaths due to it. In India, the first case was confirmed on 30 January 2020. Since then, India has accumulated over 10.2 million cases, globally the second highest, with over 148,000 deaths. Like elsewhere, India too has experienced major disruptions to various facets of life, including socioeconomic activity, employment, education, livelihood and healthcare.

COVID-19 has emerged as the most significant public health threat of the 21st century, but this may not be the last. One of the biggest lessons from COVID-19 is to trust science, and to develop policy based on evidence. Irrespective of technological prowess or political ideology, countries that followed science have done well. Leaders who refused to listen to science or followed pseudoscience led their countries down the path of disaster.

Science at work — what about economics?

Vaccines against COVID-19 are the best examples of science at work. It used to take a decade or longer to develop a vaccine, but one for COVID-19 was desired in 18 months. In less than 12 months, we already have 61 vaccine candidates in human clinical trials and another 172 in clinical evaluation. As of 28 December 2020, five vaccines have received early or limited use approval, and three have received full use approval — the Pfizer/BioNTech and Moderna vaccines in Canada and a few other countries, and the Sinopharm-Beijing vaccine in the United Arab Emirates and Bahrain. This speed is made possible due to science; technology; innovation; open sharing of information; and the public, private and philanthropy sectors working together.

India produces about three billion vaccine doses, of which about one billion is used domestically and the remaining two billion are exported. At this time, there are multiple COVID-19 vaccine candidates being tested in India. Of these, the inactivated whole virus vaccine from Bharat Biotech International Limited (BBIL) called Covaxin, and the viral vectored Oxford-AstraZeneca vaccine from Serum Institute of India (SII) called Covishield, appear to be the frontrunners. India has prioritised vaccinating 300 million people — 10 million healthcare workers, 20 million frontline workers and 270 million people above 50 years of age and those below 50 years with associated comorbidities. For this, 600 million vaccine doses would be needed. The Duke Global Health Innovation Center estimates that India will have access to 1.5 billion doses of COVID-19 vaccines. This includes 500 million doses of Covishield and one billion doses of a protein vaccine from Novavax also manufactured by SII. Further, about 300 million doses of the Covaxin and 100 million doses of the Zydus-Cadila DNA vaccine (called ZyCov-D) may also be available.

How much would the vaccines cost and who should pay for them? According to SII, Covishield would cost ₹1,000 in the open market and ₹500-600 in bulk purchases for the government. Based on this price, it would cost at least ₹15,000 crore to vaccinate 300 million people. To ensure fair and equitable access based on need, the vaccine should be free to those on the government’s priority list. Of the 30 million healthcare and frontline workers, those in the public sector should be covered by the government while those in the private sector should be covered by their employers. For the remaining 270 million, the vaccine should be available through bulk purchase at designated vaccination points. Those below an income threshold should get it free; the remaining should pay the government procurement price.

The world in 2021 and beyond

How will the pandemic play out in the next year and the year after? That will depend on vaccine availability, coverage and duration of protection. Models of global vaccine manufacturing and capacity show that COVID-19 vaccines sufficient to cover all healthcare workers would only be available by late 2021 or early 2022, for at risk or vulnerable groups by mid 2022 and for everyone by mid to late 2023. There is a developing access problem with about 9.6 billion vaccine doses already pre-booked, 40 percent by high income countries and in some cases enough to vaccinate their entire population few times over. The poorest countries may only be able to achieve 20 percent coverage through vaccines provided by the COVAX partnership. Would this global imbalance lead to a new world order in which people from countries with poor vaccine coverage face discrimination? Would movement across national boundaries depend upon vaccination certificates?

The duration of vaccine-mediated protection may be gauged from studies following natural infection. Neutralising antibodies wane off in about 3-5 months but the cell-mediated immune response may protect longer. Infection by other endemic human coronaviruses may also offer some protection. Modelling studies by researchers at Harvard University have suggested various scenarios — annual winter outbreaks if immunity lasts less than 40 weeks; outbreaks every other year if immunity is longer than 100 weeks; winter outbreaks if transmission is seasonal; or elimination by 2024 if there is cross-protection from exposure to endemic coronaviruses.[1] While these models have assumed seasonal variation like in influenza viruses, which is driven by genetic drift, SARS-CoV2 is genetically much more stable.[2] As we approach 2021, the pandemic waves remain difficult to predict.

In the last few weeks of 2020, viral variants that comprise a new lineage, called B.1.1.7 have emerged in the UK and a similar variant called 501.V2 emerged independently in South Africa—both are spreading quickly and have moved to other countries as well. India also reported six cases of this variant on 29 December 2020 in returnees from the UK. While there is concern that these variants are more contagious, the good news is that there is no evidence of increased disease severity or vaccine escape.

Since all the vaccines being developed are based on raising an immune response against the virus’ Spike protein, they will offer more or less equal protection. With increasing vaccine coverage globally, there would be fewer opportunities for transmission and this will reduce the virulence or disease-causing potential of SARS-CoV-2. Increasing vaccine coverage would also lead to evolutionary pressure on the virus to develop vaccine-escape mutants, which are observed in other viral infections following widespread deployment of vaccines. However, since this will involve changing the virus-cell binding interface, it may also lead to reduced viral fitness and virulence. This should be monitored closely over the next few years through genomic sequencing of viruses from infected people. Increased genomic sequencing will also allow us to catch variants that spread faster or cause more severe outcomes well in time.

Science has shown the way by fast-tracking COVID vaccines. We must do more by way of better communications and building trust to assure the public that the vaccines are safe and effective. For the first time in the history of human disease, we have the historic opportunity to end a pandemic through vaccines.

[1] Stephen M. Kissler, Christine Tedijanto, Edward Goldstein, Yonatan H. Grad and Marc Lipsitch, “Projecting the transmission dynamics of SARS-CoV-2 through the postpandemic period.” Science 368, 860–868 (2020). DOI: 10.1126/science.abb5793

[2] Jason W. Rausch, Adam A. Capoferri, Mary Grace Katusiime, Sean C. Patro and Mary F. Kearney, “Low genetic diversity may be an Achilles heel of SARS-CoV-2.” Proc Natl Acad Sci 117, 24614-24616 (2020). DOI: 10.1073/pnas.2017726117

Source link