Pockets of low vaccine uptake remain in Europe. Here's how 4 countries are dealing with them

About 500 people demonstrate against any compulsory Covid-19 vaccination, and the mandatory use of the health pass, on September 4 in Brussels, Belgium.

(CNN)Most European countries have Covid-19 vaccination rates that would be the envy of much of the world. But even here, hesitancy in certain areas is causing governments to take action -- or risk stalling their efforts to control the spread of the virus.

The highly transmissible Delta variant and concerns that winter in the northern hemisphere could bring a bad flu season have increased the urgency for authorities to boost vaccine uptake.
Reasons for hesitancy are varied. Some people believe they are fit, healthy and young, so getting vaccinated is not a priority. Some found it too complicated to book a vaccine so gave up. And some simply distrust their government to the extent that they've become susceptible to misinformation.
    So what are different governments doing to encourage those who have not been vaccinated, for whatever reason, to get the shot?

      Belgium: Unvaccinated urged to 'examine their conscience'

      While 72% of Belgium's population is fully vaccinated against Covid-19, rates vary widely across the country of about 11.5 million people.
      In the capital, Brussels, only 51% of the total population is fully vaccinated, according to the latest data from the country's health authority, Sciensano. That compares with 79% for its Dutch-speaking Flanders region and 67% for French-speaking Wallonia.
        Authorities are now increasing pressure on vaccine holdouts in the capital in the hope of boosting vaccination rates.
        While restrictions such as the mandatory wearing of face masks indoors have been eased elsewhere in the country, they remain in place for Brussels because of its lower vaccination rate and the strain that Covid-19 cases are placing on the city's hospitals.
        And from October 1, the regional government in Brussels will also require residents to show a "Covid pass" to prove that they have been vaccinated or have recently tested negative for the virus before they can enter restaurants, bars or fitness clubs, according to Reuters.
        This may go some way to encourage reluctant younger residents to get the shot. According to official figures, only 46% of those aged 18 to 24 in Brussels have received at least one vaccine dose, compared with 86% for the same age group in Flanders and 72% in Wallonia.
        Belgian Prime Minister Alexander De Croo had harsh words for the nation last Friday.
        "Those who do not get vaccinated are responsible for the fact that stricter rules remain necessary in some places," he said. "Intensive care is rapidly becoming a gathering place for the unvaccinated. We cannot accept that as a society. No one has the right to voluntarily put other people at risk."
        Nurses at major hospitals in Brussels wrote an open letter last week saying they were "tired and angry" at the continuing Covid-19 crisis and pleading with everyone to get vaccinated.
        Kenneth Coenye, chief medical officer at the Sint-Jan Clinic in Brussels, told CNN that during the last weekend of August, only four out of 70 patients being treated in Covid ICUs in the city were vaccinated. "It's very painful, of course, because they don't only get sick, they die. And that is so completely preventable," he said.
        Speaking Saturday, the leader of Wallonia -- Belgium's largest region -- urged citizens who have not yet received their Covid-19 vaccination "to understand the consequences of their inaction and procrastination."
        "We are not done with this damned virus because vaccination coverage remains insufficient," Minister-President Elio Di Rupo said. "The unvaccinated bear a heavy responsibility for themselves, and those close to them. The time has therefore come for everyone to examine their conscience."

        France: Health pass boosts vaccine uptake

        Measures proposed by French President Emmanuel Macron this summer have had a marked impact on vaccine hesitancy.
        Late last year, polls showed barely 40% of the French expressed any intention of becoming vaccinated. But as of September 15, nearly 64% of the population was fully vaccinated and more than 73% had had at least one dose, according to figures from Our World in Data.
        Under legislation announced by Macron on July 12, people in France have since August been required to carry a Covid health pass, or "pass sanitaire," to enter premises including bars, restaurants, cinemas and theaters, and many outdoor public spaces.
        The pass -- which shows proof of either vaccination, a negative Covid-19 test or of past infection -- is also required for travel on long-distance public transport and to visit medical facilities.