Looking to 2021: Addressing the great unknowns about COVID-19 vaccines and equity

| By Professor Teo Yik-Ying | 

The world greeted the arrival of 2021 with hope and anticipation of a return to pre-COVID normalcy, especially given the announcements that a handful of countries, including Singapore, have started vaccinating their populations against COVID-19.

The initial uncertainty over whether the COVID-19 Vaccines Global Access (COVAX) Facility will be able to honour its promise to deliver up to 2 billion vaccine doses to the 190 participating economies has now dissipated, when an announcement was made at the end of January of a concrete timeline to start dispatching vaccines to these economies.

The COVAX Advance Market Commitment also guarantees that the 92 lower- and middle-income countries (LMICs) will be able to equitably access highly subsidised COVID-19 vaccines at the same time as higher-income self-financing countries. This is necessary as LMICs would otherwise be priced out of the market if they have to bid against well-resourced countries for the same limited vaccine supply.

Ensuring an equitable distribution of efficacious vaccines to every country is a necessary step for the world to eventually return to some resemblance of pre-COVID normalcy. However, whether this is indeed as straightforward, the devil, as often the case, is in the details.

Let us examine the ‘three great unknowns’ about vaccines that continue to vex policymakers and public health scientists alike:

1. Does the vaccine prevent infection and transmission, on top of protecting against severe disease?

The present vaccines approved for emergency use by the World Health Organization (WHO) are primarily approved on the basis that they protect against severe disease and death, as those were the explicit outcomes vaccine developers defined in their late-stage clinical trials. What this means is that there is actually limited clinical trial data on whether these vaccines actually prevent a person from being infected in the first instance; or if infection is possible, to prevent infecting other people subsequently.

Without a definitive understanding on the role of vaccines against infection and transmission, governments globally have no choice but to continue the requirements of mask wearing, social distancing, and strict personal hygiene, even for people that have already received the vaccine.

However, encouraging evidence is starting to emerge that COVID-19 vaccines may just be as capable in limiting infections as in decreasing hospitalisations. A Nature article published in February reported an astounding fall in the number of infections and hospitalisations that corresponded strongly with the population rollout of COVID-19 vaccination in Israel, even after accounting for social restriction measures such as the implementation of a national lockdown.

While these are still early days and a careful analysis is needed to confirm this observation, it is clear that scientists view this as an encouraging sign that vaccines may have an effect on limiting infection and transmission, in addition to protecting against severe disease.

2. How long does the vaccine actually stay effective for?

Given that the world is relying on the COVID-19 vaccines to permit a lasting return to normalcy, we are certainly most eager to learn when their protective effects are likely to start waning. After all, this directly impacts national and global strategies on vaccine supply chains and vaccination rollout in the community, not to mention the thorny topic of repeated vaccine financing for LMICs that even COVAX is presently not actively contemplating.

Natural immunity to the four coronaviruses that are responsible for common colds are notoriously transitory, which explains why we continue to be plagued with colds throughout our lives. Should the protective immune response generated by the vaccine similarly wane with time, albeit after a longer period compared to the natural immunity from infection, regular booster vaccinations may become a reality. This was candidly outlined by the British Prime Minister Boris Johnson last month, when he said the British people will have to get used to receiving autumn booster shots to retain the protective effects, either due to waning immunity or against new SARS-CoV-2 variants.

And this leads us to the third great unknown:

3. Mutations of SARS-CoV-2 and vaccine effectiveness

Perhaps the greatest fear now is whether today’s vaccines will continue to remain effective against new variants of the SARS-CoV-2 coronavirus. Viruses continuously evolve to maintain their ability to survive and thrive in hostile competitive environments, and reports of how new emerging strains of the coronavirus are more transmissible should actually not come as a surprise. After all, when humans adapt with precautions such as mask wearing and social distancing, any mutation of the coronavirus that produces a much higher viral load or even allows farther airborne dispersion will grant the mutant strain a Darwinian advantage, thus ensuring a higher chance of successful propagation and reproduction.

Should mutations now permit the coronavirus to evade the protective effects of vaccines, as emerging evidence seem to suggest this to be the case for the South African 501.V2 variant against vaccines from Pfizer, Moderna, and Oxford-Astrazeneca, hopes that were originally pinned on the global distribution of efficacious vaccines for a return to normalcy would now need to be reexamined.

Global inequity will stifle global recovery

Compounding the three unknowns is the present global inequity in vaccine access. While COVAX aims to ensure an equitable distribution of vaccines, the present mandate primarily focuses on delivering vaccine doses to inoculate 20 per cent of the population in each participating country – estimated to be sufficient for the healthcare workforce and the elderly but far from adequate for the whole population.

What this means is that, except for the advanced economies that are capable of self-financing their vaccine purchases, most of the world’s countries may never have sufficient vaccine doses to inoculate 80 per cent of their population – a figure forecasted by infectious disease modelers to be necessary to achieve herd immunity.

How will global commerce and travel look when border restrictions remain for the most parts of the world? Health inequities that already existed before COVID-19 are likely to be compounded, and the divide between the haves and have-nots looks set to widen when economies that have traditionally relied on subsistence-based agriculture, labour-intensive manufacturing, and tourism receipts may just be the ones that will find vaccines to be priced beyond their reach.

Domestically, countries also need to grapple with the challenge of equitably distributing vaccines to oft-neglected segments of the population, which include refugees and migrant workers. The latter is especially tricky in countries with large communities of undocumented migrant workers who do not possess any legal status or health insurance. Extending national vaccination rollouts to include these people may be morally and ethically the right thing to do, but is not straightforward logistically and financially, especially in the absence of a census. How would one even determine the number of vaccine doses required or register the inoculation of these people?

The concern around ‘vaccine refugees’, where people from a resource-poor country illegally cross the border of a wealthier neighbour to be vaccinated as a refugee or undocumented migrant worker, is also a real one. In settings where there are already insufficient vaccine doses for all the citizens, inoculating non-citizens will also be politically tricky to justify.

So, while there is certainly optimism in some societies about an incipient return to pre-COVID normalcy, it is important to realise this optimism is not universal, and a global recovery can and will be thwarted by vaccine nationalism and inequitable distribution.

The journey to the light at the end of the tunnel will continue to be fraught with obstacles and uncertainties, and we would be wise to manage our expectations for 2021.


About the author

Professor Teo Yik-Ying is the Dean of the NUS Saw Swee Hock School of Public Health. Prior to his Deanship, he was the Founding Director of the School’s Centre for Health Services and Policy Research (CHSPR) and also served as the Director of the Centre for Infectious Disease Epidemiology and Research (CIDER) from 2015 to 2017. He is presently a member on the Council of Scientists for the International Human Frontier Science Program, as well as a governing board member of the Regional Centre for Tropical Medicine and Public Health Network for Southeast Asia.



Looking to 2021 is a series of commentaries on what readers can expect in the new year. This is the fifth installment of the series.

Click here to read about Professor Tommy Koh's seven wishes for the year.

Click here to read about Professor Danny Quah's outlook for the global economy.

Click here to read about Dr Kelvin Seah's analysis of the Singapore economy and labour market.

Click here to read about Professor Freddy Boey's views of the start-up ecosystem.