advertisement

Infectious Diseases

Updated 09 April 2020

Could the TB vaccine you received at birth help protect against the coronavirus? We asked an expert

The age-old BCG vaccine is currently being trialled in Australia to see if it could lessen the impact of Covid-19 in frontline workers. But what about those who received it at birth? Does it make them more resilient? An expert weighs in.

Last week, Health24 reported on the BCG vaccine that is being trialled in Australia in the hopes of fighting the Covid-19 virus pandemic.

In a nutshell, a team of researchers in Australia will fast-track the BCG vaccine in humans to see how Covid-19 symptoms respond. The study will give a BCG vaccination to frontline Healthcare workers to see if it decreased the likelihood of Vovid-19 virus infection, and potentially if infected, then the severity of disease.

Now, a new study has surfaced, investigating the correlation between the mortality rate of Covid-19 related complications and the universal BCG vaccine policies between countries.

In simple terms – are those nations who make BCG vaccines mandatory at birth less susceptible to high Covid-19 related deaths?

What the study entailed

The study was published as a pre-print on MedRvix and hasn’t been peer-reviewed yet. The authors posed the question why the impact of Covid-19 differs so greatly from country to country.

While the difference in mortality rates can be explained by various factors such as cultural norms, mitigation efforts and health infrastructures, the researchers think that the difference in mortality rate could be partially explained by the different national policies regarding the BCG vaccine during infancy and childhood.

The case in favour of the BCG vaccine – designed to provide immunity against tuberculosis – is that it appears to offer a broad spectrum of protection against various respiratory infections, which could include Covid-19.

In this paper, the authors compared a number of countries’ BCG policies with the number of Covid-19-related mortalities.

The conclusion was that countries without BCG policies such as Italy, the Netherlands and the USA seem to be more impacted by Covid-19 than those with universal and long-standing BCG policies.

The authors also found that there were fewer Covid-19 cases in countries with BCG policies – making BCG a potential new tool in the fight against the pandemic.

What about South Africa’s figures and our BCG policy?

This study provided a glimmer of optimism for South Africa, seeing that we’ve had a strong BCG vaccination protocol since 1973.

As of 7 April 2020, we have 1 749 cases of the Covid-19 virus, and the death toll stands at 13. Compared to the rest of the world, these figures are low. But could this really be attributed to BCG vaccines or simply because that the data isn't a true reflection of the South African situation?

Health24 contacted Prof Jonny Peter, Head of the Division of Allergology and Clinical Immunology at Groote Schuur Hospital, University of Cape Town for some insight to this study.

According to Peter, it is true that the BCG vaccine may offer a broad spectrum base immunological benefit against a host of respiratory infections, but the vaccine can’t be regarded as the ultimate safety net against Covid-19:

“Right now, there are one or two small human trials – so not a lot of data on humans. There is, however, some local data from an adolescent study of booster BCG vaccination in SA. They gave adolescent a booster dose of BCG to prevent against TB. As a side-effect they noted that the group that received the BCG had a considerably lower number of upper respiratory tract infections than the placebo group.”

Peter stated in a telephonic interview that the current data presented in the US study is heavily based on the recorded fatality rate, which is also heavily influenced by each country’s testing strategy. We may still be missing a considerable numbers of cases including pneumonia deaths given limited testing capacity; testing may be more in higher income settings and this may introduce a bias.

Concerns about BCG revaccination 

Regarding the Australian trial, Peter is optimistic the strategy of vaccination or revaccination of healthcare workers as a prophylactic measure could help to curb the worst effects of Covid-19 and protect those who are most exposed.

However, in a country in South Africa where we have a high rates of tuberculosis and non-tuberculosis mycobaceteria the effect may not be the same, one should be very cautious to simply roll out a revaccination programme for the sake of it and without robust data.

“You need to ensure that someone doesn’t have active TB or and immune compromised state as BCG is a live vaccine, and this could be harmful,” Peter said.

That would mean HIV and TB screening would need to be included into any planned BCG vaccine programme.

According to Peter, people shouldn’t rest on their laurels simply because they received the BCG vaccination at birth. Looking at studies in animals and adolescents that monitored the effect of BCG on the immune system for six months to a year afterwards, he is less optimistic about the idea that a single birth vaccine will protect an adult decades after receiving it at birth. All currently recommended methods should be used to limit being infected.

READ MORE | READ MORE | 8 strains of coronavirus circulating around the world

READ MORE | Could an age-old TB vaccine help in our fight against coronavirus?

READ MORE | Three countries have kept coronavirus in check; here's how they did it

Image credit: iStock