As the UAE records one million infections to date, what's next in fight against Covid-19?

'Hybrid immunity', from vaccination and prior infection, is reducing rates of serious illness

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As one million cases of Covid-19 are confirmed in the UAE to date, many will wonder how the pandemic will probably play out in the country.

While the authorities were among the fastest in the world to introduce vaccinations, the coronavirus has not gone away, with thousands of positive test results each week.

But the number of deaths has fallen in recent months, with the last time there were more than 10 recorded in a single week being back in February.

Immunity within the population, from vaccination and prior infection, is expected to be part of the reason why infections are less severe.

In June, the UAE said “100 per cent of the target groups in the country” were now vaccinated.

Prior infection and vaccination offer protection

“All the conclusions we have reached about immunity which apply to the other countries will apply to the UAE,” said Prof John Oxford, a virologist and emeritus professor of virology at Queen Mary University of London.

So, prior infection will continue to provide at least some protection, even against new variants, strengthened by vaccination, he said.

Prof Paul Digard, a virologist at the University of Edinburgh, said a distinction should be made between sterilising immunity, which completely prevents infection, and partial immunity, which stops a person from falling seriously ill.

Vaccination and prior infection may often fail to provide the former, meaning that they may not be able to prevent a person from catching the coronavirus again, as repeated infections that some individuals have experienced have shown.

Limiting effects of virus

However, protection from vaccination and prior infection does provide partial immunity, meaning that it substantially reduces the likelihood of severe illness, even if it does not prevent infection entirely.

Some studies have credited this combination of vaccination and prior infection — also referred to as hybrid immunity — with reducing the rate of hospital admissions in later waves of coronavirus infections.

For example, a study from South Africa earlier this year found that during that country’s fourth wave of Covid-19 infections, about one in 100 cases resulted in a person needing to go to hospital, while during earlier waves the figure had been as high as one in 24. Reduced pathogenicity of the virus over time may also have played a role in lower hospitalisation rates.

More recent research from Qatar found that a previous infection with one of the older Covid-19 variants, such as Alpha, Beta or Delta, provided some protection from reinfection against even two recent iterations of the coronavirus, BA.4 and BA.5, both sub-variants of Omicron.

However, the researchers found that an infection with Omicron provided stronger protection against reinfection with BA.4 and BA.5, although part of the reason may have been that Omicron has been circulating more recently than the earlier variants, protection conferred by which may have faded.

Reason for cautious optimism

Looking ahead, Prof Digard said it was likely that Covid-19 would increasingly “fade into the background of seasonal respiratory diseases” familiar before the pandemic, although it remained to be seen how long this would take.

“I think the level of cross protection you get from having seen the virus repeatedly, that builds up, and then over years that infection will get milder and milder,” he said.

“If you look at the epidemiological curve for winter flu in the 20th century, there was a massive spike in the 1918 pandemic. Over the next 70 years or so, even with the odd spike, it was a generally declining curve.

“I think SARS-CoV-2 will behave like that, hopefully rather quicker than that general decline with flu.”

While he said a country such as the UAE - with a population of about 10 million - may experience spikes in cases again, these would probably be more modest than previously.

“Not one million cases of 10 million. It’s 100,000 of 10 million,” he said. “At that point you’re maybe talking of the background winter cold that everybody gets when schools reopen or go on holiday.

“We’ll pay less attention to it. The people who grew up with it will look at it like they’ve got a cold.”

While for most it will be a mild infection, Prof Digard said that some groups, notably the elderly, would remain more at risk.

Reformulations of the vaccines may be needed to cope with the continued changes in SARS-CoV-2, Prof Oxford said, with the virus having evolved faster than many researchers expected. It will be a case, he said, of “updating the vaccines and seeing how it goes”.

A concern on the horizon, he said, is the risk of another such pandemic. Bats act as a reservoir for many coronaviruses, one of which could jump the species barrier again and start to infect people.

“The question is really, with so many bats, when is the next one going to arrive?”, Prof Oxford said.

Updated: August 10, 2022, 6:48 AM