Q&A: How does the Delta surge differ from the previous Covid waves?

There is a terrible inevitability with the Delta variant of Covid-19. Coronavirus case numbers will soar in coming weeks and come close to matching daily case numbers during the nightmare months of January and February this year.

The risk scenario is different, however, due to the vaccination rollout. The threat is diminished but still hugely menacing.

The extent to which common sense measures – social distancing (especially indoors), hand hygiene, wearing masks and ventilation – continue to be deployed will determine whether the risks are minimised. It will also dictate if opening up can be progressed successfully.

In spite of impressive vaccination rates, we are not in a position to say Ireland is winning the race between vaccination and the Delta surge, which is accounting for 80 per cent of current cases.

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How does this surge differ from early 2021?

There are two key differences. First, we have gone from zero vaccinations to a situation where 60 per cent of the Irish adult population is fully vaccinated. Second, increased transmissibility is affecting a particular age cohort on this occasion.

The Delta variant is aggressively transmissible: it goes through whole households, where the Alpha variant might have infected 50 per cent to 60 per cent of people within a family unit during January and February.

This time young people are out and about in social gatherings that would be considered “normal” in pre-Covid times and thus are especially vulnerable, although in most instances infection is minor or they are asymptomatic. This is confirmed by the latest data: 87 per cent of Irish cases over the last fortnight have been in people under 45, compared to 40 per cent in January.

Who are most at risk from Delta?

The vulnerable on this occasion are younger people as the vast majority of over-50s are vaccinated. Compounding this are indications that up to 50 per cent of GP patients who have had coronavirus are suffering from long Covid.

Long Covid symptoms vary from mild to very severe – and range across fatigue, breathlessness from even mild exertion, chronic cough and “brain fog”. They are difficult to quantify and, therefore, hard to treat.

The high level of infectivity is such that it could put at risk people who are vaccinated, though 90 per cent of this group are considered protected against hospitalisation.

Given the rise in case numbers, it is not surprising that 5 per cent of new Covid-19 cases are among people who are fully vaccinated. The vaccine should help, however, to minimise the severity of illness.

About 10-15 per cent of people aged 50 to 60 are still not vaccinated for whatever reason and they need to be really vigilant.

The bottom line is vaccines are highly effective in reducing hospitalisations, serious illness in the form of ICU cases and deaths.

With early variants, 10-15 per cent of cases ended up in hospital with a mortality rate of less than 2 per cent. It is too early to conclude if a similar pattern is happening with Delta. With younger people being most affected, it might not be the case.

How are hospitals coping?

Hospitals are preparing for a surge in Covid-19 cases, and may have to defer some categories of care, the HSE has said. If, however, Ireland follows Scotland which has seen a similar wave of Delta cases, peaking at 3,500 a day but falling back to 2,000 a day, things will prove more manageable.

High case numbers requires scaling up contact tracing. At present, the level of close contacts for every case is four, which is lower than expected. Last year it was as high as 10. A key difference on tracing this time round is deployment of rapid antigen testing to interrupt transmission, even if it is not as reliable as PCR resting.

What is likely next winter?

The longer-term picture is worrying. A potentially triple mix of Covid-19, influenza, and the respiratory virus respiratory syncytial virus (RSV) could push an already under pressure HSE to breaking point this winter.

A report by leading infectious disease experts in the UK warns influenza and RSV hospital admissions and deaths “could be two times that of a ‘normal’ year and could coincide with an increase of Covid-19 infections, and their associated long-term consequences”. The HSE’s ability to catch up with the backlog of routine care is likely to be impaired in that scenario.

If that race between vaccination and Delta cases is lost, the virus remains dominant with additional risk of more variants emerging and the health system being overwhelmed quickly.

Getting the approach wrong on “unlocking” – as many experts warn is likely to happen in the UK with its “let it rip” approach – could also allow new vaccine-resistant variants to emerge.

What is the latest advice?

Ireland has a real chance of better containment compared to other countries because of current restrictions, a high level of vaccination and an exceptional degree of vaccine acceptance – just look at Australia where there are low vaccination levels and high anti-vaxxer numbers.

Some basic advice applies. Anyone with common cold symptoms should get tested for Covid-19. The Delta variant has different symptoms: sore throat, nasal symptoms and headache, along with fever, cough, shortness of breath or changes in smell or taste.

Anyone with sore throat, headache, runny nose, blocked nose or sinus should not assume it’s a regular cold, according to the HSE. Don’t assume it is hay fever or seasonal. If it is in any way unusual then isolate and get a test.

If fully vaccinated you still risk transmitting the virus. You may also get Covid-19, or you may pass it onto younger members of your social circle who face a significant risk of long Covid – especially if they are not vaccinated. And one dose of any two-dose vaccine does not confer sufficient protection.

And as anyone in the vaccine business will tell you, the best vaccine to get – among those approved for use – is the one you can get quickest.

The race between the vaccine and the Delta variant is far from over. There is a chance to stay ahead of it in coming weeks with right response. The outcome will be known by the end of August.