The World Health Organization (WHO) may sound the global "all clear" for pandemic H1N1 shortly, says Director-General Dr. Margaret Chan. In a Canadian Press interview, Chan said the decision could be made soon after a WHO meeting that is likely to occur this week. H1N1 has lost its dominance, now behaving more like seasonal flu viruses, and the population has gained some immunity. Any delay in the decision would likely be due to continuing cases in a few areas, such as New Zealand and India. [Aug 8 Canadian press article]

The H1N1 pandemic may be abating in much of the world, but India reports 942 new cases in the past week (Aug 2-8), with 83 deaths. An article in the Times of India says two patients in the city of Pune died from pandemic H1N1 Aug 6, bringing the number of H1N1 deaths there to 99 since April. The state health department reported that 29 people are in critical condition and on ventilator support in city hospitals; 38 people tested positive for the infection Aug 6. [Indian government's case count]

The World Health Organization (WHO) reports that the global pandemic H1N1 situation remained largely unchanged in the week that ended Aug 1, with transmission still most active in parts of South Asia and limited areas of tropical South and Central America. India continues to have the most notable activity, although the intensity and severity did not appear to exceed levels during the first 2009 wave. Southern Hemisphere areas with H1N1 flu activity include Chile, New Zealand, and Australia. [Aug 6 WHO update]

A new study has identified an amino acid in pandemic H1N1 that allows its efficient replication in mammals. The acid, at position 591 of polymerase subunit PB2 (ie, PB2-591), apparently compensates for the virus's lack of the amino acid PB2-627K, thought to be critical for avian flu virus adaptation to mammals. The authors say this finding, plus another regarding an alteration in surface shape of the H1N1 PB2 protein, helps explain the spread of the virus in humans. [Aug PLoS Pathog article]

Influenza-like illnesses (ILIs) in New Zealand, now in its winter season, are showing a significant uptick, according to a news release from the country's ministry of health. Reports of ILIs are at their highest level for the year so far but remain well below the level at this time last year, just after the peak of the 2009 wave. Pandemic H1N1 is the predominant strain circulating, and some areas that were not affected severely last year are seeing higher rates of hospitalization. [Aug 5 news release]

A group of Japanese and US researchers has found that the 2009 pandemic H1N1 influenza virus and a contemporary H5N1 avian flu virus have a high degree of genetic compatibility. The study involved co-infecting susceptible (MDCK) cultured cells with both viruses. Their findings, they say, show that reassortment between the two viruses is likely in the event of co-infection in a susceptible host (likely swine) and could create a pandemic H5N1 virus. [Aug 4 J Virol abstract]

Inclusion of the neuraminidase (NA) surface glycoprotein in pandemic H1N1 influenza vaccine is likely to reduce the hemagglutinin (HA) dose required and to broaden protective immunity. Dutch researchers evaluated the efficacy of soluble, multimeric forms of 2009 H1N1 HA and NA as vaccines in ferrets. NA dramatically reduced virus replication, and HA markedly decreased clinical effects of infection; optimal protection was achieved by co-administration of both. [Aug 4 J Virol abstract]

Researchers analyzing World Health Organization Southern Hemisphere data collected during the winter of 2009 found that the pandemic H1N1 strain almost totally displaced seasonal H1N1 in the first phase of the pandemic. Also, the rates of seasonal H3N2 influenza declined from typical levels but to a lesser extent. The authors recommend that seasonal vaccines for the coming winter include representative pandemic H1N1 and seasonal H3N2 viruses but not previously circulating seasonal H1N1. [August Eurosurveillance article]

A study from Norway found that the prevalence of antibodies to pandemic H1N1 rose from 3.2% to 44.9% from August 2009 to January 2010. Young people aged 10 to 19 had the highest prevalence, at 65.3%. Population-representative serum samples were collected before the pandemic, during the early phase, and after a nationwide vaccination program. The authors state that the high immunity to pandemic H1N1 may be enough to forestall an epidemic of the virus in Norway in the coming flu season. [August Eurosurveillance article]

The frequency of pandemic H1N1 flu is rising in New Zealand's Wairarapa region, according to The Dominion Post today, with five schools reporting 20% to 50% of students affected. All told, more than 400 children are out sick. A Wellington health official said the outbreak is particularly severe and spreading rapidly, according to a TVNZ report. Radio New Zealand today reported that the country has had more than 380 confirmed H1N1 cases and 183 hospitalizations in the past 2 weeks. [Aug 4 Dominion Post story]

Researchers compared lab-confirmed pandemic influenza (871 cases) with seasonal flu (288) in Western Australia last year and found hospitalization rates slightly higher with pandemic H1N1 but many similarities between the strains. Patients in both cohorts reported a median of 6 of 11 flu symptoms, and less than half the patients in both groups had more than one underlying condition. However, those with pandemic flu were more likely to have diabetes. [Aug 3 Emerg Infect Dis study]

Researchers surveyed 13,000 Hong Kong residents at various times between April and November 2009 and noted that respondents reported low anxiety throughout that period of the pandemic. Greater anxiety was associated with poorer hygiene but greater social distancing. Over time, knowledge on modes of transmission and efforts to control transmission failed to improve and social distancing declined. The authors conclude that community mitigation played little role in mitigating the impact of H1N1. [Aug 2 J Infect Dis abstract]

Some New Zealand emergency departments struggled to keep up last week as pandemic H1N1 flu cases increased, according to the New Zealand Herald. Almost 1,900 people sought medical care for flu-like symptoms last week, with Auckland's hospitals running near capacity. Officially, 59 hospitalized H1N1 cases were confirmed for the week. Australia is also reporting a rise in cases, with several requiring intensive care, according to other media reports. [Jul 31 New Zealand Herald story]

Using enhanced surveillance methods, New York City's health department identified 996 likely H1N1 patients (929 confirmed, 27 probable) who needed hospitalization by Jul 7, 2009. Its methods, which included hospital-based surveillance and enhanced passive reporting, found that about 50% of patients lived in high-poverty areas and about as many were kids. The approach helped the city target its response and "demonstrates the need for flexibility in surveillance approaches." [Jul 30 Emerg Infect Dis study]

Israeli officials report two cases of possible lab-confirmed re-infection with pandemic H1N1. The first patient, a 26-year-old man with Noonan syndrome, developed pandemic flu in August 2009 and was discharged without antivirals or supportive treatment. His disease redeveloped last November. The second patient, a 13-year-old boy with advanced cerebral palsy, was treated for 5 days with oseltamivir (Tamiflu) in July 2009 and improved. He tested positive for recurrent novel H1N1 in December. [Jul 30 Emerg Infect Dis letter]

Researchers studied closely matched isolates of pandemic H1N1 in ferrets and found the oseltamivir (Tamiflu)-resistant strain to not transmit efficiently via droplets but to transmit well via direct contact. The oseltamivir-sensitive strain transmitted well via both routes. Although both strains caused a similar disease course, they found signs of lower viral fitness in the resistant strain. The authors said drug-resistant strains must continue to be closely monitored. [Jul 29 PLoS Pathog study]

An Australian study comparing attitudes during the pandemic with those 2 years prior showed increased hand washing but a drop in willingness to comply with certain prevention efforts. About 47% reported increased hand washing, and 28% reported increased covering of coughs and sneezes. The percent willing to be quarantined stayed about the same, but willingness to avoid public events and social gatherings for a month and to wear a mask in public dropped over the 2 years. [Aug Emerg Infect Dis study]

Mexican researchers compared more than 200,000 cases of flu-like severe acute respiratory illness during the pandemic with 60 patients with Down syndrome who reported the same flu-like symptoms in the same period. They found that those with Down syndrome were 16 times more likely to be hospitalized, eight times more likely to require intubation, and 335 times more likely to die from the disease. They recommend vaccination and early antiviral treatment in this group. [Aug Emerg Infect Dis study]

Though many are calling for the World Health Organization (WHO) to incorporate severity into its pandemic alert phases, a renowned virologist is saying no. Malik Peiris of the University of Hong Kong said there was no doubt novel H1N1 was a pandemic, well before the WHO declaration. "We really don't have good assessments of severity," he told The Hindu. "So it would completely paralyze international public health policy, I think, if severity is linked to the definition of a pandemic." [Jul 29 The Hindu story]

A seroprevalence study of 7,962 people aged 1 to 60 years found that, from August to October 2009, people had these rates of antibodies to pandemic flu: Costa Rica (26.4%), the United States (22.5%), Switzerland (16.9%), Germany (12.6%), Belgium (10.1%), and Japan (5.9%). The authors write, "The low proportion of seropositive children in Europe and Japan suggests that little local viral transmission had occurred." They say the data show that public health steps in late 2009 were justified. [Jul 29 Eurosurveillance study]

Today in Morbidity and Mortality Weekly Report, officials from Skokie, Ill.'s health department detail how they administered 40,000 doses using a five-phase H1N1 vaccination campaign. Highlights included school and day care clinics that reached a large number of staff and caregivers as well as children, targeting emergency medical services personnel, shifting unused vaccine from the school clinics to medical clinics, employing mass-vaccination clinics, and reaching out to the homebound. [Jul 30 MMWR report]