NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

[Sally Furniss]

Updated at 6:50am on 24 September 2009

Health officials believe swine flu has affected up to a quarter of New Zealanders, and many others could be vulnerable to a predicted second wave of infections.

British health authorities say a second wave may have already begun there, while Australia is poised to begin a vaccination programme.

The Ministry of Health estimates that between 11% and 25% of New Zealanders have had swine flu and would be immune in any second wave.

To confirm the figures, the ministry will to carry out a survey, which involves medical researchers taking blood from a random sample of people.

The Government is expected to receive recommendations soon on a vaccination programme, and the survey results would be used to help target the vaccine.

http://www.radionz.co.nz/news/stories/2009/09/24/1245c8643abd

 

[gsgs]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

...while we had estimates of 7%(symptomatic)-11%(all)
for New York and Australia

 

[JetStuuby]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

Henry has an article about 30%+ in Australia....

<a rel="nofollow" href="http://www.recombinomics.com/News/09220901/H1N1_Trial_Ab.html">Commentary</a>

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[JetStuuby]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

Text from the article mentioned above......


Widespread Pandemic Antibody Confounds Clinical Trial
Recombinomics Commentary 16:02
September 22, 2009

At baseline, 76 of 240 subjects (31.7%) had antibody titers of 1:40 or more on hemagglutination-inhibition assay

The above comments are from the recently completed clinical trial for H1N1 in healthy adults in Australia. Although cases with confirmed pandemic H1N1 were excluded from the study, over 31% of the participants had protective antibody prior to the first infection, signaling widespread influenza in undiagnosed adults. This high level is likely linked to limited testing, as well as the use of fever in the case definition. Thus, those without fever are not tested and are significantly under-represented in confirmed cases.

Data on symptomatic patients without fever suggests the frequency of infection without fever is above 50%. 30% of initial lab confirmed patients in Mexico, who were hospitalized because of breathing difficulties, did not have a fever. In Chile, the frequency of confirmed patients without fever was 50%. A recent study of transmission during a plane flight found that 36% of lab confirmed cases did not have a fever.

However, these figures are likely to be higher in the general population, because mild cases with no fever will not seek medical attention, or will not be tested because they do not meet the case definition, which includes fever.

Similarly, students without fever will be largely missed because guidelines cite fever AND a subset of additional symptoms, so those without fever are not considered to be infected patients. Thus, they are misdiagnosed as having colds, allergies, strep throat, bronchitis, or stomach flu, and such students frequently remain in school, infecting other students (see map).

This leads to a high percentage of infected cases in clusters that are not tested in general, and those that are tested are almost exclusively cases with fever.

Thus, the inclusion of fever in the case definition ensures significant spread by patients without fever as well as a major undercount of infections. This selective testing limits surveillance, and creates a large reservoir of virus in patients who have not been properly diagnosed.

 

[Sally Furniss]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

It is this paper
Published at www.nejm.org September 10, 2009 (10.1056/NEJMoa0907413)

Response after One Dose of a Monovalent Influenza A (H1N1) 2009 Vaccine — Preliminary Report

http://content.nejm.org/cgi/content/full/NEJMoa0907413

Michael E. Greenberg, M.D., M.P.H., Michael H. Lai, B.Med.Sc., M.B., B.S., M.Med.Sc., Gunter F. Hartel, M.S., Ph.D., Christine H. Wichems, Ph.D., Charmaine Gittleson, B.Sc., M.B., B.Ch., Jillian Bennet, M.Sc., M.P.H., Gail Dawson, B.Pharm., Wilson Hu, M.D., M.B.A., Connie Leggio, B.Sc., Diane Washington, M.D., and Russell L. Basser, M.B., B.S., M.D., F.R.A.C.P.


ABSTRACT

Background A novel influenza A (H1N1) 2009 virus is responsible for the first influenza pandemic in 41 years. A safe and effective vaccine is urgently needed. A randomized, observer-blind, parallel-group trial evaluating two doses of an inactivated, split-virus 2009 H1N1 vaccine in healthy adults between the ages of 18 and 64 years is ongoing at a single site in Australia.

Methods This preliminary report evaluates the immunogenicity and safety of the vaccine 21 days after the first of two scheduled doses. A total of 240 subjects, equally divided into two age groups (<50 years and 50 years), were enrolled and underwent randomization to receive either 15 µg or 30 µg of hemagglutinin antigen by intramuscular injection. We measured antibody titers using hemagglutination-inhibition and microneutralization assays at baseline and 21 days after vaccination. The coprimary immunogenicity end points were the proportion of subjects with antibody titers of 1:40 or more on hemagglutination-inhibition assay, the proportion of subjects with either seroconversion or a significant increase in antibody titer, and the factor increase in the geometric mean titer.

Results By day 21 after vaccination, antibody titers of 1:40 or more were observed in 116 of 120 subjects (96.7%) who received the 15-µg dose and in 112 of 120 subjects (93.3%) who received the 30-µg dose. No deaths, serious adverse events, or adverse events of special interest were reported. Local discomfort (e.g., injection-site tenderness or pain) was reported by 46.3% of subjects, and systemic symptoms (e.g., headache) by 45.0% of subjects. Nearly all events were mild to moderate in intensity.

Conclusions A single 15-µg dose of 2009 H1N1 vaccine was immunogenic in adults, with mild-to-moderate vaccine-associated reactions. (ClinicalTrials.gov number, NCT00938639 [ClinicalTrials.gov] .)


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............Immunogenicity

At baseline, 76 of 240 subjects (31.7%) had antibody titers of 1:40 or more on hemagglutination-inhibition assay (Table 2 and Figure 2A and 2C), with no significant differences between either age groups (P=0.21) or dose groups (P=0.68). Similarly, there were no significant differences in baseline geometric mean titers (GMTs) between age groups or dose groups (Table 3). Of note, baseline titers of 1:40 or more on hemagglutination-inhibition assay were observed in 48 of 108 subjects who had received the 2009 seasonal vaccine (44.4%; 95% confidence interval [CI], 35.4 to 53.8), as compared with 28 of 132 subjects who had not received the seasonal vaccine (21.2%; 95% CI, 15.1 to 28.9; P<0.001 by Fisher's exact test).

 

[Roehl_JC]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

Sounds to me like upwards of 31.7% already now have sufficient titres of antibodies from exposure in the first wave that would be enough to prevent a second infection. So does anyone conclude that this is good news? Am I right to conclude that those of us who've had the virus no longer need to get vaccinated for it?
best, jc

 

[JetStuuby]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

Might be best to continue this line of thought on this thread

http://www.flutrackers.com/forum/showthread.php?t=126281

 

[Treyfish]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

New swine flu wave expected



By JOHN EDENS in Alexandra - The Southland Times


Last updated 05:00 19/10/2009



<!-- -normal_story_landing- --><!--start components/story/common_content-->Hospitals in Otago and Southland remain on high alert as the Health Ministry expects a second wave of swine flu.
The World Health Organisation declared a phase six influenza pandemic ? a global spread of the virus ? on June 11.
Hospitals placed on code yellow ? one below the response phase ? by the Health Ministry introduced strict infection control measures.
With the arrival of spring in New Zealand the number of cases and transmission rates declined.
But the transmission of flu and rates of flu-like illnesses continues to increase in the northern hemisphere because of the early onset of winter in many countries, according to WHO.
Pandemic waves can be separated by months and an "immediate at-ease signal" in countries where incidence has fallen may be premature, according to WHO.
Health Ministry deputy director of health Dr Fran McGrath said that globally the virus continued to spread and more cases were being reported in the northern hemisphere.
She said it was important that people remained vigilant and the ministry would downgrade the standby status only if H1N1 no longer posed a risk to public health in New Zealand.
The first wave of the pandemic had abated but the virus was circulating, she said.
"Although the case numbers are now low, we expect that there will be a second wave as occurred in previous pandemics.
"We have taken stock of what we have learned from the first wave and there is considerable work already under way to be ready for a second wave," she said.
At Dunstan Hospital near Clyde infection control practitioner Joss Willyams said it was important that people realised high alert restrictions were still in place.
Anyone with a heavy cold or flu-like symptoms should not visit a hospital, she said.
There were 16 patients in Dunstan, none with flu-like symptoms, she said.
Dunstan Hospital manager Carol Horgan said visitors must not be complacent now that the incidence of swine flu had declined.
Invercargill Southern Cross Hospital manager Judy Bradley said patients would be screened for flu-like symptoms until the Ministry of Health notified any change.
Otago Southland H1N1 incident controller Leanne Samuel said that code yellow was standard in hospitals in the region.
"We're experiencing fewer people presenting with symptoms but we're still being vigilant in case a second wave appears."
SWINE FLU FACTS:
*Pandemic declared: June 11
*Number of NZ deaths: 18
*Number of confirmed NZ infections or H1N1 complications: 3175
*Worldwide reported cases: 375,000
*Worldwide reported deaths: 4500
*Pandemic codes: White, planning stage; yellow, standby phase; red, response phase; green, recovery phase. Sources: World Health Organisation and Ministry of Health :tiphat:http://www.stuff.co.nz/national/health/2976685/New-swine-flu-wave-expected

 

[gsgs]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

that's some agenda for the population.
I don't think they really expect it. We learned through the years,
that they often say what they want the people to believe
and not what they really think.

We have the experience from New York and London and the
32% with antibodies from Australia, which make a 2nd wave unlikely IMO.

 

[Giuseppe]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

The point is, according me: to schedule a vaccination campaign to avoid another wave of morbidity and mortality. It is imperative.

And - of course - to push Pharma Cos to make available trial results for injectable NAI drugs (ie: peramivir, zanamivir) and subsequently approve them for use in hospitalized critical patients cannot be treated with oral oseltamivir or inhaled zanamivir.

The winter wave in northern hemisphere temperate regions is ongoing and vaccination campaigns will be probably pointless, at least for the overwhelming majority of population.

This is a strong reminder for regions that have just passed the first wave peak.

 

[gsgs]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

yes, but no need to hurry.
Get the cheaper vax in April. Sell now for higher prices
to Northern countries

 

[gsgs]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

no serology available from areas that had a full wave,
e.g. New York.
Why is it ?

 

[Hogweed]

Re: NZ - swine flu has affected up to a 25%, and many others could be vulnerable to a predicted second wave

It's maybe not statistically significant yet but Google reckons that flu activity slightly increased in both New Zealand and Australia last week.