The first batch of A/H1N1 flu vaccines may be approved for use by some countries in September, the World Health Organization (WHO) said on Thursday.

Marie-Paule Kieny, the Director of the WHO Initiative for Vaccine Research, said several drugmakers had already produced vaccines for the pandemic and clinical trials were now underway.

"We are on track in development," Kieny said.

According to the official, initial clinical trial results of the vaccines could be available early next month and that could lead to the first vaccines being approved by regulators for use.

Meanwhile, the WHO stressed that safety should not be compromised despite the urgency to approve the vaccines for use.

"The public needs to be reassured that regulatory procedures in place for the licensing of pandemic vaccines, including procedures for expediting regulatory approval, are rigorous and do not compromise safety or quality controls," the UN agency said in a statement.

Time constraints meant that clinical data at the time when pandemic vaccines are first administered would inevitably be limited. Further testing of safety and effectiveness would need to take place after administration of the vaccine had begun, it said.

"For these reasons, WHO advises all countries administering pandemic vaccines to conduct intensive monitoring for safety and efficacy, and many countries have plans in place for doing so," the statement said.

The A/H1N1 flu pandemic has caused a total of 1,154 deaths worldwide, according to WHO's latest update on Tuesday.

The A/H1N1 influenza, which was first detected in Mexico and declared as a pandemic by the WHO in June, has so far been characterized by the mildness of symptoms in the overwhelming majority of patients, who usually recover even without medical treatment.

According to the WHO, so far there is still no signs of the virus mutating and becoming more fatal despite its rapid spread.

(Xinhua  News Agency August 7, 2009)