Coronavirus vaccines have arrived – will this rescue us?

After a great deal of public clamour, media noise, and anxious expectations, the first batch of COVID-19 vaccines have finally arrived. What can we expect?

Undoubtedly, we have in vaccines one of the most powerful weapons to combat disease. It has been said that, other than the provision of clean water, vaccines have done more for public health than any other intervention.

One only needs to look at the eradication of smallpox, the near eradication of polio, and the drastic reduction of many infectious diseases – which almost all of our young doctors of today have never seen, such as polio and diphtheria and even measles – to marvel at the power of vaccines.

Unfortunately, but realistically, we cannot have the same expectation for COVID-19 vaccines. Viruses like measles and polio behave themselves and maintain their respective vaccine targets. Not so the COVID-19 coronavirus, SARS-CoV-2. Here, we have a far wilier opponent.

Truth be told, we didn’t expect this virus to be as changeable as it is. (The genome, the total genetic structure of this virus, is a long piece of RNA, unlike the fragments of the influenza virus, and also unlike the mutable reverse transcription mechanism of the HIV virus.)

It did indeed surprise us, for it didn’t take long for its many mutations to appear. Surprise turned to anxiety when it became apparent that some of these mutations were positioned in critical parts of its structure, that very part of the virus which is targeted by the immune defensive response following infection or vaccination.

Fortunately, our immune system and our immune responses to infection are more complex than merely making antibodies, and vaccines may still work in spite of worrying signals coming from the laboratory. However, what it does tell us is that we cannot presume that what you find with many other vaccines will similarly apply to controlling COVID-19.

Nevertheless, there are two factors in our favour in dealing with the challenges of this virus. First, there is our science of vaccinology. The development of vaccines and understanding of how they work is now advanced and sophisticated. So much so that the necessary adjustments to the vaccine needed to meet the changing of the virus’ targets can be done quite effortlessly and relatively quickly.

Second, and fortunately for us, as contagious as the virus is especially in certain superspreading settings, its infectivity is considerably less than (say) measles, and the herd immunity threshold is correspondingly lower.

So, what does all this mean with regard to planning how vaccines will be used to control the epidemic? The rollout will basically be structured into two parts. The aim of the first part, consisting of two phases, is to protect those most at risk of being infected. The highest priority of these will be healthcare workers, who will be the first phase. The most vulnerable of society will be in phase two – the elderly, those with underlying illnesses (comorbidities), key personnel for the running of the country, and people living in crowded or congregate environments.

Attention can then be turned to part two, to reach as many of the rest of the adult population in order to achieve herd immunity. Children aren’t currently approved to receive the vaccine.

What do we hope the vaccine will achieve? We cannot expect it to do what the polio vaccine did for polio or the measles vaccine for measles. What we do want to see, however, is a future which avoids the healthcare system, hospitals, and healthcare workers, from being swamped, as we experienced during the first and second waves.

We will want to return to our pre-COVID-19 lives, without the restrictions, without the masks, and having functions and celebrations as before.

This will certainly not happen as soon as the vaccination kicks off. It didn’t happen in the United Kingdom, the first country to commence population immunisation. In fact, two months after commencing its rollout, the United Kingdom is in the midst of a second wave considerably more severe than the first wave, and necessitating the strictest of lockdowns.

Until herd immunity is reached, we will still need to continue strict adherence to non-pharmaceutical interventions while the vaccines do their work. That target will take many months and beyond the year to reach.

The COVID-19 pandemic will go away and vaccines will certainly play a major role together with human behaviour. The virus won’t disappear. The only virus that has ever been eradicated is smallpox.

What we are hoping for in the post-COVID-19 era is a virus which will no longer be totally new to the human population. In history, it has been those viruses introduced into totally naïve and therefore totally susceptible populations, causing so-called virgin-soil epidemics, which have devastated populations. (Measles and smallpox introduced by European invaders in the 16th century to the native populations of the Americas resulted in catastrophic epidemics, wiping out major portions of indigenous populations.) When COVID-19 is no longer new and the virus no longer meets a totally susceptible human population, immunity from vaccines and past infections will produce barriers to stop the spread of the virus.

In the future, there may well be spikes of COVID-19 respiratory infections, hopefully much more trivial, which we will come to tolerate. This will be much like we do for their coronavirus cousins, which are responsible for our annual winter colds, along with many other viruses.

Perhaps some lessons of hygiene practices may continue to be part of our everyday lives. We may well even adopt some of the cultural practices so common in the Far East, like wearing masks in public places when we have a cold, or hand-hygiene practices.

We will come out of this miserable pandemic, but the more conscientious we are about maintaining our non-pharmaceutical interventions to assist the work of vaccines, the sooner that day will come.

• Professor Barry Schoub is the Chair of the Ministerial Advisory Committee on COVID-19 vaccines. He is emeritus professor in virology at the University of the Witwatersrand, and the former director of the National Institute for Communicable Diseases.