Bangladesh’s government and aid agencies started vaccinating Rohingya refugees Tuesday as a virus surge raises health risks in the sprawling, cramped camps where more than 1 million people who fled Myanmar are sheltering.

The highly transmissible delta variant is driving an infection surge across Bangladesh, with around 20,000 infections and 200 deaths recorded so far in Cox’s Bazar district, the southern region bordering Myanmar where the refugee camps are located.

The International Federation of Red Cross and Red Crescent Societies said a national positivity rate of around 30% indicates the spread of COVID-19 is much higher, especially with cramped conditions and the risks faced by many people living in the refugee camps.

The government’s Civil Surgeon’s office in Cox’s Bazar and aid agencies began the vaccination campaign across 34 camps alongside Bangladesh’s national vaccination effort.

About 500 Bangladesh Red Crescent staff and volunteers joined the health workers for the campaign in collaboration with the U.N. refugee agency, according to a statement from the international body.

Rohingya community leaders, front-line health care volunteers in the camps, and Rohingya older than 55 are in the first group to be vaccinated. Over 65,000 of the nearly 900,000 refugees will be vaccinated in the first cohort, the U.N. High Commissioner for Refugees said in an email to The Associated Press.

“COVID-19 has spread all over the world. We came here to get vaccinated for our protection so that it does not harm us,” Nurul Islam, 65, said in a camp at Ukhiya in Cox’s Bazar, as he waited for shots alongside hundreds of other refugees.

Bangladesh has reported more than 1.3 million infections, including 22,897 deaths from COVID-19 since the pandemic began.

Experts say the full toll may be underreported, as many people don’t go to hospitals and many others died before getting tested.

Across the country’s vast border regions with India, infections from the delta variant have spread amid concern that a lack of awareness about masks and maintaining other health guidelines could lead to a deteriorating COVID-19 situation in the densely populated nation.

Less than 5% population of the country’s 160 million people are fully vaccinated. The initial campaign was interrupted in April when India stopped exporting AstraZeneca vaccines to Bangladesh, which had made a purchase agreement for 30 million doses.

The government of Prime Minister Sheikh Hasina bolstered its effort to get vaccines from other sources, particularly China, and began a new round of vaccinations nationwide starting last weekend.

The country now a good stock of vaccines, mostly China’s Sinopharm. Officials say over 3 million people received a shot in the first two days of the new campaign.

More than 700,000 Rohingya fled Buddhist-majority Myanmar in 2017 as a harsh military crackdown was waged against the ethnic group following an attack by insurgents. Other Rohingya have lived in refugee camps in Bangladesh following earlier waves of persecution.

The 2017 crackdown included rapes, killings and the torching of thousands of homes, and was termed ethnic cleansing by global rights groups and the United Nations. While Bangladesh and Myanmar have sought to arrange repatriations, the Rohingya are too fearful to return home.