The rollout of stuttering vaccines in Europe faced several hurdles on Friday as EU regulators said they were reviewing the side effects of the Johnson & Johnson shot, and France further restricted use of the AstraZeneca sting.

The US Medicines Agency said it had not found a “causal” link between the J&J vaccine and the blood clots, but its investigation continued after “some people” suffered complications.

Much of the world is still in the clutches of the pandemic, which killed 2.9 million people, from Brazil, where the virus kills more than 4,000 people a day, to Japan, where the government has tightened restrictions again.

In India, the worst-hit state of Maharashtra is running out of vaccines as the health system collapses under the weight of the contagion. Maharashtra, home of the megacity Mumbai, has been put under curfew and weekend lockdown.

Populations across Europe are facing some of the toughest antivirus measures in the world, but the epidemic cannot be contained.

The whole of France is subject to some form of restriction and the country has so far delivered bumps to more than 10 million people.

But it has repeatedly changed the rules for AstraZeneca’s vaccine, first over doubts about its effectiveness, then fears that it could be linked to blood clots.

This was the case again on Friday. Health Minister Olivier Veran said citizens under 55 who had a first shot with AstraZeneca would be given a different vaccine for their second dose.

Shortly after speaking, the World Health Organization said there was “insufficient data” to support switching Covid-19 vaccines between doses.

While Europe continues to deviate from ongoing disputes over AstraZeneca’s sting, the EU Medicines Agency announced it is looking at a second sting for blood clot problems.

The European Medicines Agency (EMA) said that the Johnson & Johnson vaccine, which uses technology similar to the AstraZeneca vaccine, reported four “serious cases” of unusual blood clots – one of them fatal.

The US Food and Drug Administration said it had not yet found a “causal” link between the bite and the blood clots.

However, “some people” in the country were found to have had clots and low levels of platelets in the blood after receiving the vaccine, and the investigation continued.

“Both conditions can have many different causes,” the agency said.

Johnson & Johnson issued a statement stating that it was aware that “all Covid-19 vaccines have reported thromboembolic events”.

However, the statement added, “No clear causal link has currently been identified between these rare events and Janssen’s COVID-19 vaccine,” referring to J & J’s European subsidiary.

Both jabs are approved for use in the European Union, but the J&J vaccine has not yet been launched and various EU countries have stopped or restricted the use of AstraZeneca.

Supply problems also hinder the introduction of vaccines.

India, one of the world’s leading manufacturers of vaccines, has its own problems with bumps in Maharashtra, where more than 100 million people live, and the economic hub of Mumbai.

“Most hospitals in Mumbai will run out of supplies by the end of the day,” Mangala Gomare, who oversees the city’s vaccination program, told AFP on Friday.

In the US, shipments of the Johnson & Johnson vaccine will drop sharply next week, US health officials warned on Friday.

In the meantime, Pfizer-BioNTech filed for approval to use the Covid-19 vaccine in 12 to 15 year olds in the United States.

The companies said in a statement that they plan to launch similar requests from other regulators around the world in the coming days.

In Europe, an AstraZeneca spokesman said half of its vaccine shipments to the EU will be delayed this week.

Swedish climate campaigner Greta Thunberg said Friday she would skip an upcoming climate meeting in the UK because countries are unable to attend on equal terms.

“Due to the extremely uneven distribution of vaccines, I will not be attending the COP26 conference if development continues as it is now,” Thunberg told AFP.

Britain has so far given at least one stab to more than 31 million people, nearly half of its population, compared to poorer countries like Mexico, which only seven percent of its population has given less than 10 million stabs.

The German central government has sought to fight the virus through restrictions on movement and trade, but several states have torpedoed the strategy by refusing to follow the suggestions.

Now Berlin is changing the rules in order to gain more central power.

The proposed adjustments are likely to result in nightly curfews and some school closings in particularly affected areas.

Japan has also tightened measures in the capital, Tokyo and other areas, particularly demanding the early closure of bars.

On the other hand, starting next week, Italy will end lockdown measures on Lombardy, the epicenter of its coronavirus pandemic, and several other regions with an improvement in contagion statistics.

And in Brazil, which has been badly hit, the Senate said it would launch an investigation into the government’s handling of the coronavirus pandemic as President Jair Bolsonaro continues to oppose lockdown measures despite new Covid-19 deaths.

Still, Rio de Janeiro lifted the current restrictions for two weeks on Friday and reopened restaurants and bars, although the city’s famous beaches remained closed.