Move would recognize that the new virus has established itself beyond North America, not that it has become more severe. But officials worry about public reaction.
This is the VOA Special English Health Report.
As of Tuesday, 73 countries had reported more than 26,000 cases of the new H1N1 flu virus. A World Health Organization official, Keiji Fukuda, said these confirmed cases included 249 deaths.
Doctor Fukuda, the agency's top flu expert, says the virus continues to spread in North America. And there are increasing reports from South America as well as from other southern countries.
Australia has had more than 1,000 cases, the largest number outside North America. The state of Victoria has been most affected.
But the United States has had by far the most confirmed cases. More than 13,000 were reported as of Monday, including 27 deaths.
The H1N1 outbreak began in Mexico in March. Mexico has reported more than 100 deaths. An unusual number of flu cases have been found in young people who were otherwise healthy.
The W.H.O. has an influenza warning system in which phase 6 means that a pandemic is taking place. In recent days the United Nations agency has moved closer and closer to such a declaration.
As of Tuesday officials had not yet announced a change from phase 5. But Doctor Fukuda said the public should understand what a pandemic means.
KEIJI FUKUDA: "By going to phase 6, what this would mean is that the spread of the virus is continued and that activity has become established in at least two regions of the world. It does not mean that the severity of the situation has increased or that people are getting seriously sick at higher numbers or higher rates than they are right now."
Doctor Fukuda, an acting assistant director-general, said the W.H.O. has been working with the member states to prepare for a pandemic. Scientists are working on vaccines to protect against the new virus. Governments have been gathering supplies of anti-viral drugs.
But public health officials have also had to consider the risks if the public overreacts to a pandemic declaration. Doctor Fukuda pointed out that hospitals might quickly fill with people who are worried but not especially sick. Then hospitals might not be able to care for other patients who really do need help.
The last flu pandemic was in 1968, caused by the so-called Hong Kong flu. Scientists say the common name for the new disease, swine flu, is misleading. The virus combines human, bird and pig viruses. But, as Doctor Fukuda pointed out, eating meat from pigs has not been a danger.
And that's the VOA Special English Health Report, written by Caty Weaver. For more health news, go to voaspecialenglish.com.