BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

[Laidback Al]

Published 6 October 2009, doi:10.1136/bmj.b3928
Cite this as: BMJ 2009;339:b3928

Research

Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009: case-control study in Mexico City

<!-- BEGIN: article --> <!-- BEGIN: legacy content --> Published 6 October 2009, doi:10.1136/bmj.b3928
Cite this as: BMJ 2009;339:b3928
Research
Lourdes Garcia-Garcia, research professor¹, Jose Luis Valdespino-G?mez, epidemiologist², Eduardo Lazcano-Ponce, research professor¹, Aida Jimenez-Corona, research professor¹, Anjarath Higuera-Iglesias, epidemiologist³, Pablo Cruz-Hervert, research professor¹, Bulmaro Cano-Arellano, engineer¹, Antonio Garcia-Anaya, engineer¹, Elizabeth Ferreira-Guerrero, epidemiologist¹, Renata Baez-Salda?a, research professor¹, Leticia Ferreyra-Reyes, research professor¹, Samuel Ponce-de-Le?n-Rosales, infectious diseases specialist², Celia Alpuche-Aranda, infectious diseases specialist⁴, Mario Henry Rodriguez-L?pez, research professor¹, Rogelio Perez-Padilla, research professor³, Mauricio Hernandez-Avila, epidemiologist⁵

Abstract

Objective To evaluate the association of 2008-9 seasonal trivalentinactivated vaccine with cases of influenza A/H1N1 during theepidemic in Mexico. Design Frequency matched case-control study.
Setting Specialty hospital in Mexico City, March to May 2009.
Participants 60 patients with laboratory confirmed influenzaA/H1N1 and 180 controls with other diseases (not influenza-likeillness or pneumonia) living in Mexico City or the State ofMexico and matched for age and socioeconomic status.
Main outcome measures Odds ratio and effectiveness of trivalentinactivated vaccine against influenza A/H1N1.
Results Cases were more likely than controls to be admittedto hospital, undergo invasive mechanical ventilation, and die.Controls were more likely than cases to have chronic conditionsthat conferred a higher risk of influenza related complications.In the multivariate model, influenza A/H1N1 was independentlyassociated with trivalent inactivated vaccine (odds ratio 0.27,95% confidence interval 0.11 to 0.66) and underlying conditions(0.15, 0.08 to 0.30). Vaccine effectiveness was 73% (95% confidenceinterval 34% to 89%). None of the eight vaccinated cases died.
Conclusions Preliminary evidence suggests some protection fromthe 2008-9 trivalent inactivated vaccine against pandemic influenzaA/H1N1 2009, particularly severe forms of the disease, diagnosedin a specialty hospital during the influenza epidemic in MexicoCity.

full article at: http://www.bmj.com/cgi/content/full/339/oct06_2/b3928

 

[gsgs]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

so, how many of the 60 had been vaccinated ?
and how many % of the total population had been vaccinated ?

8 of the 60 died ? how many controls died ?

what's "Vaccine effectiveness " , getting infected or dying



I wished someone would rewrite these abstracts,
so they are clearer, shorter and more understandable

-------------------

ha, just having written this, I found the other thread:



In a group of 60 confirmed infected and 180 uninfected controls, uninfected people were significantly more likely to have received the seasonal flu vaccine (29% v 13%). Turning the data around, of the 179 unvaccinated people in the study, 52 (29%) became infected with pandemic H1N1 whereas eight of 61 (13%) vaccinated people became infected. Furthermore, all of these eight people survived, whereas 18 of the 52 unvaccinated people who were infected died. Despite the study’s limitations, the data suggest that vaccination with the seasonal flu vaccine confers some protection against pandemic H1N1 virus infection and severe disease from this infection. . . .

------------------------------

make a bigger sample, just ask 1000 random people
1) whether they had ILI in the peak-weeks
2) whether they had had the seasonal vax

or take the 20000 confirmed Mexican ILI-cases, how many had been vaxed ?



it could be that vaxed people are denerally more careful, more aware
of flu. Have better knowledge how to avoid it


didn't we just see the Canadian study, that vaxed people were double as likely to get ****** ?

 

[Giuseppe]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

Full Free PDF article: http://www.bmj.com/cgi/reprint/339/oct06_2/b3928

 

[gsgs]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

so often we have studies with contrary results
same with surgical masks vs. N95 respirators
or effectiveness of seasonal vax
or markers required for pandemic viruses
or handwashing
or fomites vs. airborne
or seasonality

something must be wrong

 

[gsgs]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

maybe Canadians are different from Mexicans

 

[german-docter]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

so, how many of the 60 had been vaccinated ?
and how many % of the total population had been vaccinated ?

8 of the 60 died ? how many controls died ?

what's "Vaccine effectiveness " , getting infected or dying



I wished someone would rewrite these abstracts,
so they are clearer, shorter and more understandable

-------------------

ha, just having written this, I found the other thread:



In a group of 60 confirmed infected and 180 uninfected controls, uninfected people were significantly more likely to have received the seasonal flu vaccine (29% v 13%). Turning the data around, of the 179 unvaccinated people in the study, 52 (29%) became infected with pandemic H1N1 whereas eight of 61 (13%) vaccinated people became infected. Furthermore, all of these eight people survived, whereas 18 of the 52 unvaccinated people who were infected died. Despite the study?s limitations, the data suggest that vaccination with the seasonal flu vaccine confers some protection against pandemic H1N1 virus infection and severe disease from this infection. . . .

------------------------------

make a bigger sample, just ask 1000 random people
1) whether they had ILI in the peak-weeks
2) whether they had had the seasonal vax

or take the 20000 confirmed Mexican ILI-cases, how many had been vaxed ?



it could be that vaxed people are denerally more careful, more aware
of flu. Have better knowledge how to avoid it


didn't we just see the Canadian study, that vaxed people were double as likely to get ****** ?

gsgs,

let's have a review of the study data:

Retrospective case control study from a 178 bed specialty hospital (!) in Mexico city:
(The National Institute of Respiratory Diseases). Time: March to May 2009.

60 patients (study group) had been treated for pandemic influenza H1N1 (59 in hospital, 1 outpatient).

180 controls (matched by age, and as usual in case control studies: 3 x study group; who were treated on inpatient and outpatient basis for elective surgery (61 in hospital, 119 outpatient).

Vaccination rate for seasonal influenza were observed retrospectively by interviews (patients or family members) without case-blinding regarding the interviewers [possible source of study bias !].

Quote:
?Vaccine status was not, however, recorded on the medical charts so it was not possible to check the self reported information.?

Vaccination rate for seasonal influenza in the Mexican population in general (data only for different groups by age). 64-72 % (only young children < 10 years) and 78 % (adults > 50 years),
Note: Vaccination rate for young Mexican adults was not available !

Vaccination rate rate for seasonal influenza in the control group: 29 % (but only 19 % for adults > 50 years)
Vaccination rate rate for seasonal influenza in the study group H1N1: 13 % (8/60)

Note:
Age groups 21 ? 60 yr:
Controls: 114, vaccinated 30 (26.3 %)
Study group (H1N1 cases): 38, vaccinated 2 (5.3 %)

Underlying medical conditions in the control group: 120/ 180 (67 %)
Underlying medical conditions in the study group H1N1: 15/60 (25 %)

Note:
The control group (elective surgery) had more patients with underlying medical conditions (e.g. pulmonary diseases).
People with underlying medical conditions were more likely to be vaccinated with seasonal influenza vaccine (due to guidelines and national recommendations).

Comment:
Most of the Mexican people (a healthy young population) probably will have no underlying medical conditions. So, it could be predictable that the vaccination rate in the study group (previously healthy Mexicans who fell ill with pandemic influenza H1N1) would be low, at least at the beginning of a pandemic.


Fatalities in the study group: 18/60 (30 %).

None of the 8 patients who had been vaccinated died.

No difference in mortality between patients with underlying medical conditions and no underlying medical conditions in the study group.

The proportion of patients who died among vaccinated cases was significantly lower than among unvaccinated cases (0/8 (0%) v 18/52 (35%), P=0.047).

Note: Statistical significance (versus random) , if P < 0,05.

Quote:
?These results are to be considered cautiously?

Comment:
IMO the main problem of this study is the predictable high vaccination rate of the control group (and a predictable low vaccination rate in the study group). IMO it would have been adequate to choose another cohort as a control group.
Thus, a low vaccination rate for seasonal influenza in the patient group MIGHT NOT reflect the real CAUSE for morbidity and mortality due to an infection with pandemic influenza H1N1 in the study group.

 

[gsgs]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

where did you get the general Mexican vaccination rate ?

can it be so high ~70% , even if 10y-50y are excluded
but only 29% in the control group
and 13% in the case-group


anyway, in the case-group we have

18 out of 52 non-vaccinated died
0 out of 8 vaccinated died (p=0.26, not so significant)

 

[german-docter]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

where did you get the general Mexican vaccination rate ?
can it be so high ~70% , even if 10y-50y are excluded
but only 29% in the control group
and 13% in the case-group


anyway, in the case-group we have

18 out of 52 non-vaccinated died
0 out of 8 vaccinated died (p=0.26, not so significant)

Quote:
Limitations of the study
(...)
"Among our control population the frequency of influenza vaccination during the previous season by age group (64% for children aged 6-35 months, 38% for children aged 3-9 years, and 19% for adults older than 50) was lower than vaccination coverage reported nationally (72%, 64%, and 78%, respectively). Since national estimates for vaccination coverage were not available for young people and adults aged 10-49, ..."

http://www.bmj.com/cgi/content/full/339/oct06_2/b3928

 

[gsgs]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

thanks, I searched for "vaccination rate" invain.
Now, that's a big difference, ~70% vs. ~30%
how can it happen ?

they still draw their conclusions ... too tedious to check the details

US-studies should confirm it (if true)

 

[Niko]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

ha, just having written this, I found the other thread:



In a group of 60 confirmed infected and 180 uninfected controls, uninfected people were significantly more likely to have received the seasonal flu vaccine (29% v 13%). Turning the data around, of the 179 unvaccinated people in the study, 52 (29%) became infected with pandemic H1N1 whereas eight of 61 (13%) vaccinated people became infected. Furthermore, all of these eight people survived, whereas 18 of the 52 unvaccinated people who were infected died. Despite the study?s limitations, the data suggest that vaccination with the seasonal flu vaccine confers some protection against pandemic H1N1 virus infection and severe disease from this infection. . . .

Other thread is here: Ordinary flu jab may protect against H1N1 - study

 

[North44]

Re: BMJ: Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009

maybe Canadians are different from Mexicans

What are you implying?

I suspect both studies are flawed. Unfortunately, this is making it very confusing for the average person.