Herd immunity in Malta: fact or fiction?

Following the announcement from Health Minister Chris Fearne that Malta has reached herd immunity as 70% of the adult population has had a COVID-19 vaccine, the British press has been flooded with articles on how it’s possible for UK tourists to visit this summer. 

A plethora of tabloids in the UK showcased the Maltese islands in all their scenic glory, alongside headlines explaining how British tourists can visit from 1 June… and get paid for it. Malta remains on the UK’s amber list.

Entry of British tourists is subject to presentation of a PCR test no older than 72 hours, proof of two vaccines, or having a PCR on arrival and quarantine in a hotel chosen by the government at a price of  €100 a night. The ministry has not announced which hotels are involved or how the selection process was made.

Fearne also said that by 1 July, other measures will be relaxed. If infection rates remain low, vaccinated individuals may be able to socialise outside without a mask, and some feasts may be allowed to take place.

But these claims of “herd immunity” and 70% of the population being vaccinated, have raised several questions. These include whether the figures relate to one vaccine or two. 

In January, the 70% target was set by the European Commission that said that by summer 2021, 70% of Europe’s population should be vaccinated. This, they said, would “put Europe on track for herd immunity”.

In April, European Internal Market Commissioner Thierry Breton spoke of his confidence that the EU would be able to supply enough vaccines to ensure the “collective immunity” of the population. They stated that this rate would be 70%.

President of the European Commission Ursula Von der Leyen also said in April that population immunity was imminent. This would be achieved when 70% of the population had at least one dose of a vaccine.

While the EU wasn’t clear in its initial communication whether this 70% related to one or two doses of the vaccine, in April, Von der Leyen clarified it referred to “at least one”.

Meanwhile, Opposition MP Edwin Vassallo tabled a parliamentary question to the Deputy Prime Minister and Health Minister Fearne on 31 May. He asked how many people had received either AstraZeneca, Moderna, Pfizer, or Johnson & Johnson vaccines. He also asked for clarification on how many had taken the first and the second dose.

Fearne’s reply was to refer the Opposition MP to an earlier reply given on 24 May, which said: “By the end of April this year, 98,330 doses of Vaxzevria (AZ) vaccine had been administered, 19,517 by Moderna and 218,001 by Comirnaty(Pfizer)”. (No, we did not get the dates wrong, that is what the PQ shows).

Fearne also announced on 24 May that Malta has “achieved herd immunity” with 70% of adults given one dose, while 42% are completely vaccinated. MP Vassallo’s question was to ask for figures following this announcement.

A document from the government’s website, most recently updated on 6 May states: “The percentage of people that need to be immune to obtain herd immunity in the case of COVID-19 is still unknown but experience from other vaccinations suggests that at least three-fourths of the population needs to be vaccinated to achieve the expected result.”

The World Health Organisation states that herd immunity percentages vary depending on the infectious nature of the particular virus. In the case of COVID-19, it states:

“The proportion of the population that must be vaccinated against COVID-19 to begin inducing herd immunity is not known. This is an important area of research and will likely vary according to the community, the vaccine, the populations prioritised for vaccination, and other factors.”

In terms of when someone can be considered ‘fully vaccinated’, the US Centre for Disease Control (CDC) states that this can be claimed two weeks after the second dose of a two-dose vaccine, and two weeks after a single-dose vaccine. It adds that those who have been “fully vaccinated” can start to do some things they stopped doing because of the pandemic.

It’s also worth noting that there is no general consensus between the world’s leading medical institutions and organisations on topics like how vaccines stop the spread of the virus. They also admit to not knowing how long COVID-19 vaccines offer protection, how effective they are against new variants, and the exact level required for herd immunity.

A number of experts believe that herd immunity through vaccines may not be possible. Mayo Clinic states that issues like vaccine hesitancy, uneven vaccine rollout, not knowing how long vaccine immunity lasts, and whether vaccinated people can still transmit the virus, means there are no certainties at the moment.

The University of Missouri states that herd immunity may only be possible if vaccination rates reach 90%. Renowned data scientist Youyang Gu said that herd immunity is not possible and we can only hope for a rate that allows some semblance of normality. Yale Medical School put the figure nearer 85%.

In short, the claim that 42% of the Maltese population with two doses and the remaining 28% with both doses (70% in total) means Malta has herd immunity, is questionable. 

There is currently no consensus on herd immunity due to the countless uncertainties around mutations, vaccine efficacy, duration of immunity, and even the way the community that is vaccinated interacts and functions.