/ 13 August 2021

Vaccine hesitant? An expert answers questions people have

Spain Health Virus Art
To the rescue: In Barcelona, a man wearing face mask walks by a work by Italian street artist TvBoy named The Three Vaccines, depicting the graces dressed in AstraZeneca, Moderna and Pfizer labels, which consciously references Raphael’s classic painting The Three Graces. (Josep Lago/AFP)

The vaccination debate has been raging on social media, further polarising South Africans at a time when the Covid-19 pandemic and the response to it has been wreaking havoc with our lives, health and livelihoods.

With more than 15-million tests conducted, 2.5-million positive cases and 75 000 people succumbing to the virus, vaccine hesitancy is a growing issue in the country. South Africa is still in the top 20 countries with the highest number of active cases.  

About 30.4% of the world population has received at least one dose of a Covid-19 vaccine, and 15.8% have been fully vaccinated.

But the numbers are ticking up with about 7% of the population fully vaccinated and 6% partly vaccinated. 

There is a lot of misinformation out there and so, to gain a proper perspective, the Mail & Guardian asked Professor Wolfgang Preiser, the head of the division of medical virology in the department of pathology in the faculty of medicine and health sciences at Stellenbosch University and the National Health Laboratory Services to answer some important questions about the vaccine.

Are the J&J and Pfizer vaccines currently in use in South Africa safe?  

Yes, they are very safe. There may be some minor side-effects (which may put one into bed for a day or two, as happened to me). These are fairly common, but nothing to worry about. Just do not plan anything major for the day after you get your jab. Significant side-effects do occur but very rarely. 

As expected, these were not picked up during the phase three clinical trials, because they are so rare that even testing the drug, in this case, the vaccines, on tens of thousands of volunteers might not reveal them. When the drug is then used on hundreds of thousands or millions of people, such rare adverse events will show up. This is why continuous monitoring needs to be done  abroad as well as in South Africa. 

While very significant for those affected, the positive side is that these adverse events were detected promptly. Very quickly, risk factors were determined (some of which are now recognised contraindications to those particular vaccines) and diagnostic and treatment protocols were also developed very quickly. Together these measures reduce the already small risk even further. 

What are the recorded side-effects?
It is important to realise that anything happening to a vaccine recipient over a period of time, usually several months, needs to be reported and investigated. Hence the reports of “dozens of people dying” after receiving the vaccine. 

But if one vaccinates 100 000 octogenarians, it is absolutely expected that a few hundred of them will die every few weeks, vaccinated or not. Yet they will all be listed and only after a review of the causes of death will the cases be defined as vaccine-related or not. 

How long did these vaccines take to move through trials?

That happened very quickly; the reason being that because of the lavish funding made available by many countries, the different phases of clinical trials could happen almost concurrently. Usually, one would do them one by one and after each decide whether the preliminary results are promising enough to warrant further investment. Here the investment risk was carried by the public purse allowing the process to move ahead quickly. That said, several vaccines did not make it. This is totally expected and proves that the outcomes were not predetermined. The trick was to front-load the race: pick several promising candidates and throw enough money at them to move ahead quickly and irrespective of commercial risk considerations. 

What are they effective against? In other words, are they less effective against some variants than others?

All approved vaccines, here in South Africa and other countries with stringent regulatory frameworks, for example, the European Medicines Agency, the UK, the US Food and Drug Administration, give very good (albeit not perfect) protection against severe disease and death. They are less effective at preventing infection per se (which is called sterilising immunity). Certain “variants of concern”, now especially Delta, are able to overcome immune responses to some extent so that the protective efficacy against them is lower than against the “wild-type” (original) virus.

What is more important or effective: infection-acquired immunity or vaccine-acquired immunity?

Usually, one would probably have to say natural immunity beats vaccine-induced immunity, like in diseases such as measles and rubella. However, our immune systems are not very good at reacting to and protecting from infections of the mucosal surfaces; examples are not just influenza and Sars-CoV-2, but also genital papillomavirus infections. In these cases, vaccines given systemically [straight into the muscle tissue] elicit good systemic immunity that may protect better than natural infection.

Will being vaccinated stop me from getting Covid-19? 

The vaccine is probably not going to stop everyone from getting infected (even from two weeks after the final dose — it takes that long for immunity to be fully developed), nor from mild disease. But it is likely to prevent the development of severe and life-threatening illness. Unfortunately, it seems that with the Delta variant, those who become infected despite vaccination (so-called “breakthrough infection”) are also capable of transmitting the virus. That is a real spanner in the wheels because it means that the “herd effect”, protecting even those who are not themselves vaccinated, is weakened. 

(John McCann/M&G)

Is a wait-and-see approach to vaccination detrimental?

Because we are still very much in our third wave — and a fourth wave is likely to happen at some stage — I suppose many people are seeing what I am: people left, right and centre becoming infected. One can safely predict that over time, anyone who has not been vaccinated will become infected. In fact, we probably have to expect that everyone will become infected, likely several times, over the years to come. This includes the vaccinated but for them infection will be much less severe.  

How long is a vaccine effective for, and can I top up with a different brand if I have already been vaccinated? 

To answer the first question, we do not know for sure. The reason is that the vaccines have not been around for long enough. A lot of data comes from “surrogate markers”, that is determining antibody titers (a type of blood test that determines the presence and level [titer] of antibodies in the blood in vaccinated people). This is useful, but not necessarily the full picture. 

Regarding the second question, there have been some natural experiments. For instance, Germany advised the below-50s not to get a second Astra-Zeneca shot due to the clotting issue, so that these people ended up getting their second shots using Pfizer. That shows that the so-called “heterologous prime-boost” works well in some combinations. 

It seems too early to recommend that and too early to make recommendations for booster doses. Let Israel and other countries go ahead and collect the evidence before we go there.