H1N1 Spread in Mexico Study

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A study shows closing schools and other social distancing measures were effective in reducing H1N1 flu in Mexico. Gerald Chowell-Puente, assistant professor for the ASU School of Human Evolution and Social Change, discusses the study.


José Cardenas: When the H1N1 flu pandemic happened in 2009, approximately 1500 deaths were attributed to the virus in Mexico. According to a new study, there is evidence that suggests certain social distancing measures prevented the further spread of h1n1 in that country. With me to talk about the study is Gerardo Chowell-Puente, assistant professor for the ASU school of human evolution and social change. Welcome to "Horizonte."

Gerardo Chowell-Puente: Thank you.

José Cardenas: Your story is particularly interesting because you were involved almost from the beginning in helping figure out exactly what was going on. Tell us about that.

Gerardo Chowell-Puente: Right, from the beginning, from the spring of 2009, when Mexican researchers and the Mexican government and was trying to understand --

José Cardenas: You were here in Phoenix and asked to go down there and help them?

Gerardo Chowell-Puente: That's correct. I flew in mid April to meet with Mexican researchers to try and understand what was going on. By analyzing the data that was coming this in terms of how many cases were hospitalized and how many dying and so forth. So, the first question we had was how transmissible the virus was and what were the age groups most affected and how severe this was, right?

José Cardenas: And you came up with surprising findings.

Gerardo Chowell-Puente: Yes, indeed. One of the interesting results we found at the beginning was the fact that the young individuals, most affected. In terms of morbidity and mortality which is a strong contrast where usually you see the very young and old are the most affected.

José Cardenas: At some point, you determined this was indeed a pandemic and had some connection with the 1918 influenza epidemic that killed millions of people.

Gerardo Chowell-Puente: That's right. We noticed that senior population, the older population, older than 60 years, were enjoying some protection. So there was more cases and in young adults, proportionally than all the population and we explained that as a result of similar virus that had been circulating back in the 1950s, should a descendant of the 1918 influenza virus that actually killed between 40 and 100 million people in the world at the time. And the older populations were enjoying immunity indeed.

José Cardenas: Tell us about the steps that the Mexican government took to deal with the outbreak.

Gerardo Chowell-Puente: Yes, the Mexican government They quickly make decisions in terms of social distancing, they decided to close the schools in Mexico city on April 24th, very early, when they noticed that the virus was spreading, being transmitted from person to person and there was a significant number of people hospitalized in intensive care units and closed the schools and decided to close large public gatherings --

José Cardenas: Soccer matches.

Gerardo Chowell-Puente: Restaurants in Mexico city, and three days after, they decided to actually close the schools all over Mexico.

José Cardenas: These were fairly controversial decisions.

Gerardo Chowell-Puente: Because disruptive measures and it was not clear whether this virus was going to continue to cause a lot more deaths so the government had to make a decision and -- with the data that was available at that time, and the decision was that if we're able to stop transmission by closing the school, we can save time later to develop a vaccine and institute other measures as well.

José Cardenas: And did the initial conclusions that you and your team members make in Mexico in the early days, have any impact in how the disease was dealt with here in the united states?

Gerardo Chowell-Puente: It had impact, I believe, all over the place, because it was the same virus seen all over the world, so we suggested that resources to focus on younger population, rather than the older populations from the very early data that was available. So there's any vaccine available, the data was suggesting that young adults should receive the important resource.

José Cardenas: This was a shortage of vaccine early --

Gerardo Chowell-Puente: Right, there was no vaccine, and it took about several months, it was not until mid-November when for example, the U.S. Had the first set of vaccine, about 40 million, it was actually very late after the first initial wave, the first wave in the U.S. And the second wave in Mexico. So -- and this is a new virus and takes time to develop a vaccine. It's actually made of fertilized eggs so it -- fertilized eggs and took a while.

José Cardenas: Given the slowness of developing the vaccine, the fact it was officially a pandemic and roots in the 1918 global pandemic that killed millions, why didn't we have more fatalities?

José Gerardo Chowell-Puente: Well, I think for example, the Mexican government closed the schools and made a very large campaign to make aware the population about the virus spreading and found transmission was reduced anywhere between 29 and 37 percent.

José Cardenas: You're talking about the most recent study?

Gerardo Chowell-Puente: This is the most recent study.

José Cardenas: To see if that worked?

Gerardo Chowell-Puente: Exactly.

José Cardenas: And your conclusions were what?

Gerardo Chowell-Puente: Somewhere between 29% and 37% of transmission was reduced in the very early stages of the pandemic. So this potentially saved us some time.

José Cardenas: And so this is the social distancing you were talking about?

Gerardo Chowell-Puente: This is the social distancing and young individuals, particularly school-aged children have high contact rates and also they are a lot more susceptible to infection. That reducing transmission rates among these age groups can reduce transmission rates among all other age groups in the community as well.

José Cardenas: There was concern in the united states, even here in the phoenix metro area that people were overreacting and you had schools being closed with just a few students seeming to have symptoms. Do you think in retrospect and based on your findings that's legitimate criticism. That people were overreacting?

Gerardo Chowell-Puente: It may seem like overreaction, but when you're dealing with a new virus, you don't know what it is, you have to really take the -- to take care of the population and in this case, in Mexico, there were a significant number of young adults hospitalized and a significant number of individuals were dying, actually, for example in the U.S., the first 18 pregnant women that got infected with the virus, about a third them, actually died from infection. So all of these signals had to be put together to make a decision.

José Cardenas: We've only got about 30 seconds left. So what's the most significant lesson learned from this experience with h1n1?

José Cardenas: We learned that social distancing interventions when they're put in place early for a significant amount of time, in this case 18 days, the government of Mexico decided to close the school, it's possible to actually stop transmission, to reduce transmission of influenza spread and this can give you more time in order to develop a vaccine that could be available for later waves of infection.

José Cardenas: On that note, we'll end our interview.

Gerardo Chowell-Puente: Thank you very much.

José Cardenas: Next week on "Horizonte," in Sounds of Cultura, the growing presence of latino singers in opera. Find out why and meet members of Los Tres Tenores, The Three Tenors, a group who recently performed here in the valley. That's next thursday at 7:30 on "Horizonte." That's it for us tonight. For all of us here at "Horizonte," I'm José Cárdenas. Have a good evening.

Gerald Chowell-Puente:Assistant professor, ASU School of Human Evolution and Social Change;

H1N1 in Mexico Study

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