Hospitals in China are reported to be filling up with Covid patients after infections surged when the country relaxed its lockdown rules.
The government says it is ramping up its vaccination programme.
What are China's Covid rules now?
In December, China dropped mass testing in cities and regions where there have been outbreaks.
People are no longer required to go into quarantine in state facilities if they or someone they have been in contact with tests positive.
There are reports of hospitals filling up with patients and a growing demand for funeral services.
Because it has ended its mass testing programme, Chinese authorities no longer have reliable figures for the number of Covid infections.
The World Health Organization (WHO) has asked it to provide specific data on disease severity and hospital admissions.
The WHO has also asked for more data on vaccination rates, especially amongst vulnerable groups and those over 60 years old.
The EU has confirmed that it's ready offer surplus vaccines to China, which has so far largely relied on its own home-produced vaccines.
How many people have been vaccinated in China?
Official figures for November 2022 suggest Chinese health authorities have now vaccinated 40% of over-80s with two jabs and a booster.
People in this age range are the most vulnerable to the virus.
This is a big improvement on China's past performance.
In April 2022, fewer than 20% of over-80s had had two jabs and a booster.
China is now reported to have set a goal for 90% of its over-80s to receive either the initial two vaccination jabs, or both plus a booster, by the end of January.
However, vaccinations alone may not be enough to halt the surge in Covid cases.
Experts believe that because the Chinese population has been locked down so much, many people have not picked up "hybrid immunity".
This means they haven't gained protection both from being vaccinated and from being exposed to the virus through other people.
Why have so few elderly people been vaccinated?
When China's government started rolling out vaccines in late 2020, it prioritised the working-age population.
It did not test its vaccines on many elderly people, and told them it could not say whether the jabs were safe for this age group.
The head of China's Covid expert panel, Prof Liang Wannian, says that made some people reluctant to get their jabs.
"Many old people have underlying diseases," he says. "They reckon it won't be safe to get vaccinated."
Are China's Covid vaccines effective?
China has mainly used only its domestically-produced vaccines: CoronaVac, made by a company called Sinovac, and Sinopharm.
Both use parts of a dead coronavirus to expose the body to Covid and stimulate the immune system to produce antibodies.
But studies suggest they are less effective than the mRNA vaccines made by Pfizer and Moderna, widely used in Western countries.
Research published in December last year, which looked at data from Singapore, found that mRNA vaccines worked better than Chinese vaccines in preventing severe illness in the over-60s.
These train the immune system to attack the spike protein on the virus - the part of the virus which infects the body's cells. They offer greater protection against severe disease or death.
Why has China not used Western Covid vaccines?
China claims to have made about half of all the world's Covid vaccine stock. But the government has not given approval to foreign-produced mRNA vaccines for general use in mainland China.
BioNTech, the German company which partnered with Pfizer to produce a Covid vaccine, has also worked with a Shanghai-based company, Fosun Pharma, to develop the same mRNA-based vaccine.
This has been made available to German nationals living in China, and is also available in Hong Kong and Macau. However, it is not currently authorised for the Chinese mainland market.
China is reported to be developing its own mRNA vaccines, and although one has been given approval for emergency use in Indonesia, it is not being used in China at the moment.
When asked about the EU offer to send surplus stock of its mRNA vaccines, a Chinese official spokesperson, Mao Ning, said that China already had an adequate supply of vaccines.
"China's Covid situation is predictable and under control," she told a news conference on 3 January.