Chandrakant Lahariya | All vaccines have minimal, but rare risks; don't worry over Covishield

In February 1998, the prestigious medical journal Lancet published a study linking the MMR (Measles, Mumps and Rubella) vaccine with autism. Before this study, though this vaccine was administered to millions of children, such linkage was never reported. In the years which followed, parents were reluctant to get their children vaccines and the MMR vaccination coverage dropped in much of Europe. The efforts to eliminate these diseases had been derailed. Several countries in Europe witnessed an increase in measles, mumps and rubella cases and disease outbreaks.

A few years later, it was revealed that the lead author of the paper, Dr Andrew Wakefield, had used fraudulent data and had financial gain by making such claims. In January 2010, the General Medical Council -- the regulatory body for physicians in Britain -- cancelled the practicing license of Dr Wakefield.  He was not allowed to practice medicine any longer. In February 2010, the Lancet retracted that paper, which essentially meant the findings were not valid as scientific evidence any more. However, in the intervening 12 years, the damage had already been done, and many children suffered from diseases which were completely preventable by vaccines.

The publishing of that now-retracted paper had given a cause to the people who deliberately oppose vaccines, which resulted in an increased vaccine hesitancy in public across the world. In early 2019, the World Health Organisation identified vaccine hesitancy as one of the 10 global public health challenges.

In the Covid-19 period, we heard many rumors about vaccines. It was due to high vaccine hesitancy that coverage remained low, and people were unwilling to get vaccinated. At the root of vaccine hesitancy is misinformation, and sometimes misunderstanding. The benefits of vaccines are proven and known. The vaccines prevent infections and diseases which result in hospitalisation and deaths. There are studies which have estimated that over the last two centuries vaccines have prevented billions of hospital visits, and millions of hospitalisations. Today, if children live longer, it is partly attributable to the vaccines which prevent and protect them from severe illnesses.

However, it needs to be remembered that vaccines are not completely risk free. There is always some risk associated with vaccines -- which could be linked to components of vaccines, or merely the process of administering an injection. In fact, such risk is associated with any other oral medication as well. One of the safest medicines -- paracetamol -- can also cause some harm or liver injury. Yet, there is one difference between vaccines and other medicines. The drugs or medicines are administered to sick people, so people are more willing to accept the associated risk, while vaccines are usually administered to healthy individuals. It is this backdrop; the countries and researchers always make an attempt to make vaccines safer. When regulatory bodies give approval for vaccines, they always weigh the benefit of vaccination in comparison to the risks involved.

There is one message which needs to be better communicated to the public but not done is that the vaccines are safe but they do have some minimal and rare risks. It is in this backdrop that the recent news of AstraZeneca, manufacturer of ChAdOx1 vaccine, produced as Covishield in India, and rare side effects of blood clotting should be interpreted. This is not a new revelation. Even after the licensing, it was found that this vaccine resulted in a rare adverse event of Thrombosis with Thrombocytopenia Syndrome (TTS). These incidents were reported more commonly in those below 30. Experts believed that there was some ethnicity linkage to these rare adverse events and these were more common in the European population. These rare events were reported with Johnson & Johnson’s Janssen vaccine -- another adenovirus vector vaccine, thus scientists considered it as the class effect -- the event was associated with a certain class/type of vaccines. All of these have been well documented in vaccine-specific scientific literature published in the last three years, and is not a new revelation.

All currently licensed Covid-19 or other vaccines are safe and effective. Each of those have some risk of adverse events. Most of the vaccine adverse events are minor such as fever or injection site pain, and disappear after some time, even without any treatment. Very rarely, some serious adverse event may happen, but that much risk we all accept in life. Just because a bus or train accident happens very rarely, or once in a few years, or an air crash takes place, we still keep travelling in these modes of transport as the benefits are far higher, and the probability of an accident is very low.

A question is being asked: should those who received Covishield worry? The short and clear answer is there is no reason to worry. The studies and vaccine safety data used for the AstraZeneca vaccine have not indicated any increased adverse event or clotting-related event in India. More important, all such rare but severe vaccine adverse events usually happen within 30 minutes to a few weeks. They are not reported after six weeks. Therefore, there is no reason to worry. These vaccines and all the vaccines which are licensed by the government have far greater benefits and very minimal risk. These vaccines are not being administered now as Covid-19 is not a serious disease any longer. However, the benefit of all licensed vaccines is proven and the risk much smaller. If need be, these vaccines will be used.  

In fact, it is time for all societies and all countries to expand the benefits of vaccines to additional population groups such as adults, the elderly, and those with pre-existing co-morbidities. There are untapped benefits of vaccines for additional population segments.