As it grapples with a surge in Covid-19 cases, Israel offers a sobering lesson that vaccination is not enough to prevent the spread of the coronavirus.
The country is recording tens of thousands of new cases each week and while deaths are not climbing as fast as in earlier waves, 122 people died from Covid-19 in the most recent weekly figures.
The easily spread Delta variant is partly to blame for the rise, which has sparked fears that the country’s hospitals could become overwhelmed.
It raises concerns that other nations could face similar scenarios, especially as children go back to school in the coming weeks in many parts of the world.
In this context, for how much longer will measures such as mask wearing and social distancing continue to be needed even in highly vaccinated populations? Or will they always be required?
What can Israel tell us about the next wave?
The requirement to wear masks indoors was reintroduced two months ago, not long after it had been lifted, when case rates began to increase.
During the latest surge in infections, those vaccinated earlier have been found to be at higher risk of falling ill. That could be because their immunity has waned over time or because earlier vaccine recipients tend to be older or more vulnerable.
It does seem, though, that protection from the Pfizer-BioNTech vaccine, which Israel has administered widely, fades faster than expected.
Around 59 per cent of those in hospital with Covid-19 in Israel are fully vaccinated, although a third booster halves the likelihood of over-60s being admitted.
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Why must we wear masks and socially distance?
Data released by Public Health England this month indicated that being fully vaccinated makes a person less likely to catch the coronavirus.
However, if a person does become infected with the Delta variant, vaccination status has little effect on the viral load (the amount of virus in the body) or the likelihood of that person passing the virus on.
Given that vaccines do not prevent transmission, Prof John Oxford, emeritus professor of virology at Queen Mary University of London, said “it would seem a sensible decision” for people to continue to wear masks.
“If you get vaccinated, it may stop you from dying, it may stop you from getting ill but it won’t stop the virus entirely,” he said.
"Now, going into the autumn and going through the winter, the respiratory virus season, I will certainly continue with my mask and with social distancing. It’s the sensible thing to do.”
Is there an end in sight?
In some nations, such as England, legal requirements for people to socially distance or wear face coverings have ceased, although some people continue to take these precautions.
Whether these measures will continue to play an important role in combating Covid-19 may depend, suggests Prof Oxford, on how effective later Covid-19 vaccines are at stopping the virus from spreading.
“It all depends on the scientific fight back,” he said.
“These first-generation vaccines, everyone is very pleased to have them but there could be something more powerful in the next generation, keeping people actually virus-free. It may be possible to get a vaccine to prevent people excreting virus.”
Later-generation vaccines should, it is hoped, also be better at combating new variants, be easy to manufacture and store, and offer long-lasting protection.
How long will public obedience continue?
Public obedience to strict measures tends to wane over time. And once rules are dropped, they are difficult to reintroduce.
Although Asian nations in particular have a strong tradition of taking precautions to prevent the spread of disease, many countries including the US, UK and across Europe have seen protests against mask-wearing, lockdown and other measures.
Dr Andrew Freedman, an infectious diseases specialist at Cardiff University in the UK, said reintroducing social distancing and mask-wearing in countries that had already eased such laws would be difficult.
“In the UK, social distancing has pretty much gone,” he said.
“So long as numbers in hospitals remain low and deaths remain low, there’s going to be a reluctance to bring in more stringent measures having relaxed them."
If social distancing and mask-wearing are not employed widely, Dr Freedman suggested measures such as good hygiene, ensuring ventilation in indoor spaces and administering booster jabs could also help to limit the spread of the virus.
