Experts Say That Vaccines Cannot Fully Protect Against COVID-19; Still Possible to Be Infected After Vaccinations

On Sunday (11 Apr), there appeared a case of a vaccinated individual infected with COVID-19 on our shores.

The 23-year-old migrant worker had received his two doses on 25 January and 17 February but tested positive for the virus on a positive polymerase chain reaction (PCR) test.

So should you be worried that the vaccines have been rendered useless? And what does this mean for the nationwide vaccination programme?

You Can Get Infected Even After Getting Vaccinated

Yes, you still can get infected. But there is no cause for concern.

This is because the primary goal of vaccines is to prevent the COVID-19 disease rather than infection.

As Professor Ooi Eng Eong from the Duke-NUS Medical School explains, “Vaccinated individuals would have developed immune memory against the Sars-CoV-2 virus such that upon natural infection, the rapid immune response would prevent these individuals from becoming ill.”

How does this help stop the spread then?

When infected persons don’t fall ill, they don’t develop symptoms like coughing or sneezing either. Real-world data from vaccinated countries show that asymptomatically-infected individuals rarely transmit the virus to another person.

But vaccines are no foolproof weapon against the pandemic.

The Ministry of Health (MOH) notes that it is possible for an individual to be infected just before or just after vaccination since it typically takes a few weeks for an individual to build up immunity after taking the shots.

Furthermore, the strength of the immune response might depend on our bodies. Associate Professor Hsu Li Yang, an infectious diseases expert at the NUS Saw Swee Hock School of Public Health, noted that sometimes, our bodies are simply not able to mount an adequate response after exposure to the virus.

This can happen to those with weak immune systems, and even in those with normal ones. However, Dr Hsu reassured that such cases occur across all vaccines, not just COVID-19 ones.

In short, there’s no need to worry. Getting vaccinated helps the whole community build up immunity against the virus!

Can a Vaccinated Individual Infect Others?

As mentioned earlier, virus transmission is likely to be low because infected (vaccinated) individuals no longer develop symptoms like coughing and sneezing, which is how the virus is passed from one person to another.

According to TODAYonline, worldwide studies have shown that individuals that are successfully vaccinated with mRNA vaccines—such as the Pfizer-BioNTech and Moderna vaccines—have shown that their risk of infection is lowered by at least 90%.

Therefore, it is crucial that the population is vaccinated as quickly as possible as few other measures are able to reduce virus transmission so quickly, added Dr Hsu.

In rare cases, some vaccinated individuals do pass on the virus to non-vaccinated individuals. This phenomenon is currently being studied and experts are keeping a watchful eye on countries that have more than 60% of their population vaccinated to understand how infections are being curbed there.

To read more about mRNA vaccines, click here!

Vaccinating The Population

Experts agreed that 70% of the adult population should be vaccinated in order to achieve herd immunity.

How exactly did they arrive at this number?

Associate Professor Cook, vice-dean of research at the NUS Saw Swee Hock School of Public Health explained that in the early days of the outbreak of COVID-19 in Wuhan, China, the reproduction rate of the virus could have been two to three.

This meant that for every 10 infected individuals, they could infect 20 to 30 people before they recover.

As such, for a country to achieve herd immunity, 50 to 66% of the population has to be vaccinated with a perfect vaccine.

However, taking into account that vaccines are not perfect and that not all groups in the population can be vaccinated safely, Dr Cook suggests that Singapore “really should be aiming for as many adults as possible to get vaccinated, ideally 80 to 90%.”

In addition, the presence of COVID-19 variants like the E484K (or Eek) mutation lowers the efficacy of existing vaccines—the efficacy rates of the Pfizer-BioNTech and Moderna vaccines then drop to a mere 62%.

Therefore, a higher vaccination rate would be beneficial to safeguard the entire nation.

An End in Sight?

The Straits Times also reports that once more progress is underway, the vaccination programme may finally bring an end to the things we’ve come to love and hate: mask-wearing and safe management measures.

Dr Cook mentioned that “[o]nce enough people have been vaccinated, the marginal benefit within a society to continue broad-based control policies such as mask-wearing becomes much reduced.”

“I doubt we’d really need to continue the mask-wearing and safe distancing,” he added. Yay!

Though, as a precaution, contact tracing, testing of individuals, and the monitoring of the situation overseas is expected to continue.

Feature Image: BaLL LunLa / Shutterstock.com