A resurgence of coronavirus in Greece and its Mediterranean neighbor Israel have taken both countries by surprise and threaten to put a damper on a much-anticipated return to normalcy just as the summer tourist season begins in earnest. Greece registered more than 10,000 positive cases a day in the three 24-periods leading up to Friday and Israel’s “coronavirus czar,” Salman Zarka, said that hospitals across the country were reopening their designated coronavirus wards due to the spike in Covid-19 cases.

The situation may be the more worrisome for Greece, which is far more dependent on tourism than Israel. On the popular island of Santorini, one-third of tests are coming back positive for coronavirus, while in nearby Mykonos the number climbs to 51 percent, the Greek newspaper Ta Nea reported on Friday. In Greece the upsurge appears to be driven by the BA.4 and BA.5 types of the Omicron coronavirus subvariant, while in Israel the BA.5 subvariant has been detected in more than half of the tested cases.

Both of the coronavirus subvariants appear to avoid antibodies from vaccination and prior Omicron infection, studies suggest. CNN reported that new data from researchers at Beth Israel Deaconess Medical Center, of Harvard Medical School, showed that antibody responses are thin among both people who had previous Covid-19 infection and those who have been fully vaccinated and boosted.

That is particularly troubling as the two countries, like many others, grapple with whether to encourage a fourth “booster” shot of existing vaccines that do not seem to be up to the task of warding off infection from the new Omicron subvariants. Israel was the first country to offer a fourth booster dose to older segments of the population and also the first country to raise serious questions about its efficacy. The same confusion is now manifesting itself in countries like Greece, where the government opened an online registration platform for the fourth dose for anyone over 30 on Thursday despite assurance from the health ministry that a fourth shot was not being considered for the general population.

Also at issue is whether governments in Greece and Israel will reintroduce restrictions like indoor mask mandates to help keep the spread in check. They had only recently been scrapped; Israel lifted its indoor mask mandate on April 24 and in Greece right now the only places where masking is required is in public transport, including the interior of passenger ferries to the Greek islands, and healthcare settings. Despite this, the government encourages people to wear masks in crowded settings whether they are indoors or outdoors. 

The so-called sixth wave of coronavirus, even though it may be less severe and lead to fewer hospitalizations than in previous waves, is already causing headaches for travelers. Tour operators, for one thing, cannot demand that their clients wear masks when the government does not require it, but when any individual falls ill while traveling it can be hugely disruptive nonetheless. If a tour leader gets sick, the logistics fallout multiplies. 

Greece is also a very popular destination for vacationing Israelis, with several flights a day connecting Tel Aviv to Athens and popular Greek islands such as Rhodes. In the capital, Israelis are now a common sight at privately run coronavirus testing centers even though Covid testing is no longer required for entry to Israel.

In addition, the surge in what has perhaps been prematurely billed as “post-pandemic” travel has caught many European airports unawares, with staff shortages and flight cancellations leading to a stream of reports about overcrowding and hours-long delays at airports large and small throughout the Continent. Compounding this challenging situation is that airports are no longer requiring passengers to wear masks — some never did — possibly putting American travelers at the most risk only hours before they fly back home.