Photo taken on May 18, 2020 shows a logo in front of AstraZeneca's building in Luton, Britain. AstraZeneca, which is developing a possible vaccine against COVID-19 in partnership with the University of Oxford, on Wednesday put on hold the phase-3 trial of its vaccine following an unexplained illness in one trial participant in Britain. (Photo by Tim Ireland/Xinhua)

Europe should consider using Chinese vaccines, Chinese experts said, after at least nine European Union countries suspended AstraZeneca's COVID-19 vaccine after serious adverse events were found. 

At the same time, Europe is facing a shortage of vaccine supplies, another challenge to the ambitious 70 percent adult inoculation rate by the end of summer.  

Health authorities in Denmark, Norway and Iceland on Thursday halted the use of AstraZeneca's COVID-19 vaccine, following reports that some inoculated people died due to blood clots after taking doses of the vaccine.

The move by the three Nordic countries came after Austria, Italy, Estonia, Lithuania, Luxembourg and Latvia lost trust in the vaccine, at least in some batches, in which post-vaccination deaths from coagulation disorders and an illness from a pulmonary embolism occurred. 

Reuters reported the three countries said that they are investigating a possible link between AstraZeneca's vaccines and serious adverse events like blood clots. 

The European Medicines Agency said on Thursday that there is no indication that AstraZeneca's vaccines are linked to an increased risk of blood clots, media reported. 

Some Chinese experts reached by Global Times said that it is almost impossible to cause thrombus with an adenovirus vector vaccine. However, if adverse events appear, the vaccine suspension is reasonable and cautious.

Tao Lina, a Shanghai-based vaccine expert told the Global Times on Friday that it can't be ruled out that there were quality defects during production. 

According to the BBC, AstraZeneca vaccines are being manufactured locally by the Serum Institute of India, the world's largest vaccine manufacturer, with more than 50 million doses a month.

Feng Duojia, president of the China Vaccine Industry Association, told the Global Times on Friday that although the Chinese CanSino vaccine is also an adenovirus vector vaccine, it has not encountered serious adverse events like blood clots. 

AstraZeneca and CanSino vaccines are almost the same technically, but AstraZeneca uses gorilla adenovirus, while CanSino uses human adenovirus as the carrier of the coronavirus protein gene, which has a higher level of suitability with the human body, experts said. 

"Because there is wide range of people being vaccinated in Europe, it's most likely that the people who had adverse reactions also had other hidden diseases," Feng said. 

An analyst said that such serious adverse events can lead to a decrease in people's willingness to inoculate in Europe, which also faces a shortage of vaccines, a huge challenge to achieving herd immunity in 2021.

In an interview with Western media, EU Commission President Ursula von der Leyen criticized AstraZeneca for failing to deliver the shots it had promised to EU countries.

She admitted that the EU was too late to approve COVID-19 vaccines and "overly optimistic" on production. Von der Leyen once said that by the end of summer, 70 percent of European adults should have been vaccinated. 

The EU has only approved the vaccines of Pfizer, Moderna and AstraZeneca. But roll-outs have been hampered by delivery delays, production bottlenecks and political blunders, Al Jazeera reported. 

"Given the shortage of vaccines in Europe and the problems with vaccines, I would suggest the EU prepare several more vaccines, such as Chinese inactivated vaccines, which have mature technology and are easy to save," Tao said. 

"China and the EU have yet to reach full mutual recognition of vaccines, so the approval process for importing Chinese vaccines will be cumbersome…But EU countries can talk to China on their own," Feng said. 

So far, Hungary and Serbia have received Chinese vaccines, and Poland expressed interest in buying Chinese vaccines in early March.

If the WHO could play a bigger role in international vaccine recognition, it would make it much easier to share vaccines from one region to another, Feng said. 

As for adverse reactions, experts said people don't need to worry too much. 

"Overall, vaccines are safe and effective against COVID-19, and adverse reactions [if any] would be tolerable for most people. Even the adverse reactions are much safer than being infected," Feng said.