One reveler at last year’s Mardi Gras celebration may have been the catalyst for 50,000 cases of the
It’s well-known that the 2020 Carnival celebration in
But researchers now believe a single person likely brought the virus to the city in the weeks before Fat Tuesday and spawned tens of thousands of infections due to people crowded together and sharing food and drinks without masks.
They suspect that the ‘Patient Zero’ of Mardi Gras infected 800 people within the two weeks separating February 13 the conclusion of the festivities on Ash Wednesday, February 26.
And those 800 then went on to spread the infection to another 50,000 people in Louisiana and neighboring states.
The team – which consisted of several institutions including the Scripps Research Institute, Tulane University and Louisiana State University Health Shreveport – says the outbreak went mostly largely undetected due to a lack of testing and mitigation efforts in place at the time.
A new study determined that a single person, likely traveling from Texas, brought COVID-19 into New Orleans for Carnival 2020. Pictured: The risk of where the virus spread in the U.S. in the first week after Mardi Gras
By Mardi Gras and Ash Wednesday, almost 800 people were likely infected, and led to 50,000 cases in Louisiana’s first wave. Pictured: Percentage of people who traveled from others states to New Orleans before Mardi Gras 2020
There was little genetic variety in the samples found in New Orleans, which created conditions similar to a cruise ship in which an outbreak hails from a single source. Pictured: Bourbon Street in New Orleans on Mardi Gras day in February 2020
Studies later showed that COVID-19 exposure rates were close to 10% in Louisiana’s first wave from March 9 to May 15. Pictured: The Society of Saint Anne parade during Mardi Gras in New Orleans, February 2020
‘Back then, there were no precautions. No one.was thinking about this,’ study co-author Mark Zeller, a researcher at Scripps, told DailyMail.com.
‘No one was wearing masks, no one was socially distancing, just partying as the previous year.
‘But the problem was the virus was already there. The virus was most likely introduced before Mardi Gras and it just got kicked-started, and dramatically increased transmission like a snowball.’
For the study, which has yet to be peer-reviewed and was published on pre-print server medRxiv.org, the team sequenced genomes of the virus from New Orleans and other locations in Louisiana during the first wave, from March 9 to May 15.
These were then then compared with genomes from the U.S. and globally to pinpoint the emergence of COVID-19 in The Bayou State.
There was little genetic variety in the sample found in New Orleans, which created conditions similar to a cruise ship in which an outbreak hails from a single source.
Infections were spread to other states, such as Texas, Mississippi and Alabama, but stay-at-home orders prevented the virus from spreading much further (above)
‘I think there’s a lot of people in a relatively small space, that’s a fair comparison,’ Zeller said.
‘Obviously the scale of Mardi Gras is way, way bigger but it was a super-spreading event, that basically happens like a cruise ship.
‘You have one infected person coming in and the virus, starts bouncing around on the ship. Think of Louisiana as like one big ship, where the virus got in and just got dramatically amplified by Mardi Gras
They also looked at mobility data to gather who was traveling into and out of New Orleans during Carnival.
Between February 14, 2020, the start of the celebration and February 25, Mardi Gras Day, more than one Americans visited the city.
The first case of COVID-19 in Louisiana was reported March 9. Unlike early outbreaks in New York and Washington, the researchers determined Patient Zero was not from Europe or Asia but from someone traveling domestically.
An analysis determined that the ill person likely came from Texas, which was more than twice as likely as the next most probable state to be the source.
This is because, during February 2020, Texas passengers accounted for 13 percent of travel to New Orleans, and 35 percent of travel to Shreveport, a city in northwest Louisiana.
Approximately 800 people were infected by the following day, Ash Wednesday, which went on to spread the virus to other and lead to about 50,000 confirmed cases, mostly in Louisiana during the first wave over the next few months.
‘The rapid nature of the early COVID-19 epidemic in New Orleans likely resulted in thousands of additional cases, which is supported by seroprevalence studies showing exposure rates of close to ten percent by May 15, 2020 in New Orleans,’ the authors wrote.
‘Compared to neighboring states that did not experience the same explosive first waves as Louisiana, the CDC…estimated that the seroprevalence in Louisiana was 35 percent to 134 percent higher than in other states in the Southern U.S.’
And while the strain in New Orleans did lead to infections in other parts of Louisiana and other Southern states, including Texas, Mississippi and Alabama, stay-at-home orders appeared to help the virus spreading to other states.
This year, New Orleans is closing down bars from February 12 to February 17 and no establishment will be allowed to sell to-go alcoholic drinks. Pictured: A group of revelers on a balcony toss beads to the crowd below on Bourbon Street on Mardi Gras day in February 2020
‘It was sort of a perfect storm. Very few people in US were conscious of the epidemic about to become so everyone was still behaving normally,’ Zeller said.
‘If Mardi Gras has come three weeks before, the virus would not have been there or the amplification would have been much much lower.
‘It also works the other away around so if Mardi Gras was one month later, everyone would have ben aware of the virus and it would have been canceled, It was just unfortunate timing of the event.’
This year, Mardi Gras and Carnival will look much different.
Bars will be closed from February 12 to February 17 and no establishment, such as restaurants, will be allowed to sell to-go alcoholic drinks.
Pedestrians and vehicles will not be allowed on some of the city’s most popular streets from 7pm to 3am and there will be no parking zones in effect as well.
Indoor gatherings will be limited to a maximum of 10 people and outdoor gatherings to a maximum of 25 guests.
‘Vaccinations are ramping up but only a very small percentage of the population is vaccinated right now,’ Zeller said.
‘We should still behave for still a couple of months. As soon as we stop wearing face masks, stop social distancing, the virus will pop back up and spreading again.
‘People should not have parties…I know everybody is fed up with the whole situation but this is not the right time to start partying.’