Dr. Shyam P Lohani

The ongoing vaccination drive is the biggest in the history of mankind. In recent times, several news portals and social media have warned of breakthrough infections in people who were fully vaccinated against COVID-19. These reports led to the mistaken impression that vaccines do not provide protection and they can exacerbate reticence among people yet to get the jab. But such breakthrough infections are not only known to occur following COVID vaccination. They frequently occur after inoculations against influenza, measles, and many other diseases.

The COVID-19 vaccines work extremely well. Still, no vaccine is 100 per cent effective. There is, however, a small chance that we could catch the coronavirus even after being fully vaccinated. The vaccines provide good protection against severe infection, hospitalisation, and death. But, they are less effective at protecting completely against infection and there are reports that many people who have been fully vaccinated are still getting Delta infections, albeit with mild symptoms.

Transmissibility
When a vaccinated person has tested positive for the disease producing agent, it is said to have a “breakthrough” case but it does not mean that they will become ill or transmit the infection to someone else. Most vaccinated people who are infected do not have symptoms, and only a few of them have mild illnesses. Early research showed breakthrough infections are rare. However, few recent studies have shown that breakthrough infections of COVID-19 are about 0.05 per cent.

The vaccines were developed with the aim to keep us out of the hospital and to keep us from dying and vaccines are even more successful than anticipated. The protection from vaccination varies from person to person depending on age and underlying health conditions. People with weakened immune function because of age or a pre-existing illness can still become seriously ill and die even after vaccination.
The big worry is that the Delta variant seems to be able to colonise people fairly well, even after vaccination. Those who are vaccinated but contracted COVID-19 are then probably being able to transmit it to other, however, at a much lower rate than by unvaccinated people.

One of the leading questions about a breakthrough case is how frequently infected people transmit the virus to others. Research has shown that fully vaccinated people may also be less likely than unvaccinated people to transmit the virus on to others. It may be due to having a smaller viral load on average and therefore likely shedding fewer viruses. However, it is still unknown whether a vaccinated person with a breakthrough infection may still be contagious to others.

Fully vaccinated people against COVID-19 are greatly protected against severe illness, hospitalisation, and death. But it is unfortunate that the coronavirus cases among the fully vaccinated are still being seen in many countries. New COVID strains such as the highly infectious Delta variant, which is now prevalent around the world, have complicated the efficacy profile of the vaccines. There are also incomplete data into how long immunity from COVID-19 lasts following vaccination.

Most of the vaccines which are authorised for use offer good protection against getting infected. However we can also see that there is still a risk of infection, as no vaccine is cent per cent effective, and we know that some fully vaccinated people can still become infected from the virus. Although vaccine efficacy varies from one person to another, most vaccines have some breakthrough infections. It must be highlighted that people with full vaccination are significantly less likely to suffer from a COVID infection.

At this time, it is still uncertain that administering an additional booster will actually enhance protection and reduce Delta variant infection. Scientists are currently evaluating the potential benefits of booster shots especially for the immune-compromised who may have more difficulties in developing a strong defense against the virus. However, many international agencies say that people who have been fully vaccinated do not need a booster shot.

Vaccination
The possibilities of the development of new Coronavirus variants are high when there is a large number of susceptible populations (unvaccinated) and high transmission rates. The best way to combat the Delta variant is to get people vaccinated as quickly as possible, thus to reduce the chances of transmission as well as the possibility for the emergence of a new variant.
The studies have shown vaccines provide powerful protection against the Delta variant; the available vaccines may be less effective than they were against earlier coronavirus strains. In such a situation, it is feared that the coronavirus evolving to a point where it requires a once-a-year vaccine, as is the case with influenza. In such a case, it is highly likely that to find out the variants that are circulating and vaccines modified by targeting dominant variants.

Few countries have recommended that fully vaccinated people once again wear masks in public indoor settings in areas of substantial or high transmission. Lastly, the best way to protect people from the virus that causes COVID-19 is to get vaccinated as soon as possible. It is also recommended that, even after vaccination, wear masks, adhere to social distancing, and avoid crowded place.

(Prof. Lohani is the founder and academic director at Nobel College. lohanis@gmail.com)