This is the boring bit of the pandemic, as we lurch towards the finish line

Vaccination hasn’t been the expected silver bullet, especially against the Delta variant

The novelty has long worn off, the existential fear has faded, and yet the finishing line seems far away; this really is the boring bit of the Covid-19 pandemic.

Mass vaccination was supposed to be the ultimate solution to the crisis, but it seems to be struggling to do the job on its own.

Covid-19 vaccines were never going to provide complete protection for everyone. But against the Delta variant, they are straining to provide the expected high-enough wall of immunity.

This mean achieving protection through herd immunity looks like an unreachable goal, while the notion of “zero Covid” through the complete elimination of the virus appears unsustainable.

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Vaccines still do a pretty good job of preventing serious illness, but their reduced effectiveness against the dominant Delta variant means achieving population immunity is “mythical”, in the words of one UK scientist this week.

We knew no vaccine would be 100 per cent protective and that some people would get infected with Covid-19 despite being fully immunised. The rise in case numbers that we have seen was forecast.

Partly, it is because there are still plenty of unvaccinated people out there. Ireland’s vaccination statistics are impressive, with about 80 per cent of adults fully vaccinated and 90 per cent at least partly dosed.

Others will have some degree of immunity due to recent infection, but that still leaves large numbers at risk of infection by a variant which is much more contagious than previous strains.

Early days

The other factor is lower-than-expected vaccine performance. It is early days in terms of assessing their effectiveness against the Delta variant, but one survey in the UK found fully vaccinated people had only a 50 to 60 per cent reduced risk of infection once asymptomatic carriers were taken into account.

In the US, researchers found the effectiveness of the Pfizer vaccine had fallen to just 42 per cent against the variant, with Moderna performing better with an effectiveness of 76 per cent.

Latest reports from Israel suggest Pfizer's vaccine is just 39 per cent effective against infection, down from 64 per cent weeks earlier as Delta became dominant. The vaccine was 88 per cent effective against hospitalisation.

More positive UK research points to the Pfizer vaccine being 88 per cent effectiveness against variant-driven disease.

Cases tell us less than they ever did, now they are occurring mostly among younger people. As the State's deputy chief medical officer Dr Ronan Glynn reminded us during the week: "When we see cases in vaccinated people, we need to remember what we are not seeing. What we don't see is the very many more infections, hospitalisations and deaths that have been prevented by vaccination."

Dr Glynn cited an 80 per cent effectiveness figure for vaccines against disease and 95 per cent against hospitalisation. He said the protection against severe disease was holding up in the context of the variant but made no equivalent claim in relation to getting infected by the variant.

Viral loads

Vaccinated people can transmit the disease to others. If infected with the variant, they appear to have the same levels of virus in their nose as unvaccinated people, though viral loads seem to fall more quickly. They are less likely to pass on the virus because they are less likely to get it in the first place, but some onward transmission will happen.

As more people get vaccinated, the proportion of cases involving vaccinated people grows. But only six out of 169 adults in ICU since April were fully vaccinated. Seven out of 155 deaths in this period involved fully vaccinated people.

The overall situation is confusing and still evolving. Denmark is getting rid of masks; Israel is re-introducing them.

It points to a future where Covid-19 is an ever-present threat, often flaring up in regions and sections of society with low vaccination levels.

We won’t be able to eradicate the virus in society but we can largely protect ourselves through vaccination.

At times, other measures may be needed to ensure hospitals don’t get overcrowded, or classrooms have to shut. That’s why there is renewed talk of mask requirements, and why visiting restrictions may be tightened.

"Vaccines are not perfectly effective: we will need to help them by taking simple hygiene measures to prevent infection," National Public Health Emergency Team official Prof Philip Nolan observed this week.

With rising cases being matched by impressive vaccination figures, it is not yet clear whether extra measures will be needed in Ireland. Case numbers are forecast to peak within weeks, but this coincides with the return of schools and the onset of autumn and winter.

Another positive is that tweaked versions of the vaccines are likely to improve effectiveness against the Delta variant, meaning further restrictions may be largely avoided.