Pfizer/BioNTech vaccine could reduce Covid-19 viral load - what it means

Wednesday, 10th February 2021, 9:26 am
Updated Wednesday, 10th February 2021, 10:26 am
The Pfizer/BioNTech vaccine could be reducing the viral load - what does that mean? (Photo: TIZIANA FABI/AFP via Getty Images)

New data gathered by researchers in Israel suggests that the Pfizer/BioNTech Covid vaccine is reducing the viral load of the virus.

Israel has already vaccinated around one in three residents, after beginning its vaccine deployment program on 20 December.

‘60 per cent smaller viral load’

According to a paper which was published on Monday (8 Feb), positive test results of patients aged 60 and over had up to 60 per cent smaller viral loads on the swab, compared to the 40 to 59 age group.

The paper explains that this is because, by this point, at least 14 days have passed since more than 75 per cent of the over-60s age group received their first dose, in comparison to the 25 per cent of 40 to 60 year olds.

While the results are based on only partial data - since the researchers did not know if the individual samples came from a vaccinated person or not - the results appear encouraging.

It shows that, once someone is vaccinated, even if they have the virus in their system, they are less likely to transmit it on to someone else because they have fewer infectious Covid-19 droplets in their noses and throats.

‘Vaccine doesn’t just protect the person who has received it’

The study said: “Previous studies have shown that viral load has been associated with transmission rates and Covid-19 disease severity.

“Therefore, our results indicate that while vaccinated individuals might be positive, they have lower viral load and therefore can be less infective and might also experience a milder disease.

“Our findings highlight that vaccination does not only protect the individual who receives it, but is likely to reduce viral shedding and therefore transmission in the population.”

‘Significant reduction of viral load’

Speaking to Times of Israel, Professor Yaniv Erlich, head of the MyHeritage lab, said: “Our result reflects great data, because it gives exactly what we want from a vaccine, namely that it reduces transmission.

“It shows, to some extent, that this reduces viral load in the nose and throat, which is the main channel of transmission of the virus.”

Erlich said that further research is required to calculate the exact direct impact of vaccination on viral load.

He commented: “The results reflect a statistically significant reduction of viral load, and we know from many studies in virology that people will be less likely to transmit if their viral load is lower, though it’s hard to estimate at this point to what extent.”