Lessons from the case where a teacher without vaccine infected half of the class with covid-19 in the US – 14/09/2021

As schools in New York City — home to the largest education network in the US — reopen their doors to all students, while covid-19 vaccination rates have stagnated between Americans and Delta variant advances, the country and the world discuss the safety of children back to school.

Children, from the beginning, have been proportionally less affected than adults by the Sars-Cov-2 coronavirus, but remain susceptible especially if they are surrounded by adults who are not vaccinated or who do not comply with sanitary protocols, as shown by a study by the Center for Control of US Diseases (CDC) (see case details below).

This Monday (9/13), according to The New York Times, 1 million New York children returned to classrooms, most of them for the first time in 18 months. All employees of the city’s Department of Education will be required to be vaccinated, by order of the city.

But mandatory vaccination, as well as the use of masks, is still a controversial issue in the US.

With regard to masks, according to a survey by the Associated Press, as of August, only ten American states and the capital Washington DC followed CDC recommendations and required all students and educators to wear facial protection.

Thirty-two states left the decision in the hands of school districts or parents. And eight states, contrary to the recommendations, passed laws or executive orders preventing the use of masks from being a requirement.

With regard to vaccination, President Joe Biden said in a speech last week that “90% of school staff and teachers are vaccinated (in the country). We need to reach 100%.”

The teacher who ended up infecting half the class with covid-19

In this discussion, a study produced by the CDC has recently gained notoriety, detailing a case that occurred in California, which illustrates the importance of preventive measures in schools to ensure the protection of students and educators.

On May 25, according to the CDC, the Marin County Department of Public Health was notified that an elementary school teacher had tested positive for covid-19. She had not been vaccinated.

Over the next few weeks, another 26 cases of covid-19 (symptomatic or asymptomatic) were identified among schoolchildren and their relatives.

The students, in turn, were under 12 years old and, therefore, could not be vaccinated yet, according to the regulations in force around the vaccines approved in the USA (here in Brazil, only adolescents over 12 years old are being vaccinated with the vaccine from Pfizer; so far, CoronaVac has had a request denied by the National Health Surveillance Agency to apply it to children aged three years and over).

In the Californian teacher’s classroom, it was identified that half of the students (12 out of 24) ended up being contaminated.

Another outbreak of contamination in the same school occurred in another class, apparently when a student had a “slumber party” at their home.

“The epidemiological link between the two classes remains unknown, but it is believed to be due to interaction within the school,” says the CDC.

The case – in which everyone recovered from mild cases of covid-19, without the need for hospitalization – brought important lessons, as the CDC study points out.

BBC News Brazil also requested the analysis of Brazilian pediatrician Daniel Becker, who is a member of the UFRJ’s Collective Health Institute and the Rio de Janeiro City Hall’s Scientific Committee for anti-covid actions.

Here are some of the most important points:

Symptoms, even if simple, should not be ignored

The teacher in question (who was not identified), according to the CDC, began to show symptoms of covid-19 – in her case, nasal congestion and fatigue – from May 19, but worked for two more days feeling fever, cough and headaches before being tested (and testing positive) on May 21st.

The professor believed it was allergy symptoms, but the case underscores the importance of not letting even mild symptoms pass – particularly at a time when the Delta variant is advancing, which is much more transmissible than the original version of the coronavirus.

Some of the symptoms of delta are similar to those of a common cold—such as nasal obstruction, runny nose, cough, sore throat, fever, headache, poor appetite—which can make them go unnoticed.

This attention to symptoms should also be given in the case of children, who should not be sent to school at all if they even present a runny nose, explains Daniel Becker.

“We have to be careful and test all children with fever or runny nose, after the fourth or fifth day (of symptoms), with an antigen test (which is done by inserting a swab in the nose and whose result that it leaves a few hours later)”, says the doctor —noting, however, that even with Delta, severe covid-19 cases in children are still rarer than in adults and that alarmist reactions are counterproductive.

“The important thing is to be very careful with the children and keep a watchful eye, even if their parents have been vaccinated — because occasionally we can have serious cases”, he adds.

It is always worth remembering that, in the case of covid-19, even asymptomatic (and vaccinated) people can transmit the virus, although cases are rarer than among unvaccinated groups.

In the case of the California study, everyone who tested positive for covid-19 spent ten days in isolation, as well as people who had contact with them. Infected rooms were temporarily closed and sanitized during this period.

The importance of the mask

A highly politicized subject in the US, the mask demonstrated its importance in the California school episode.

The CDC investigation pointed out that the teacher in question appears to have breached the local requirement to wear masks in closed spaces and read aloud to her students – speaking out loud, without a mask, is one of the ways we inadvertently scatter more droplets of potentially contaminated saliva.

The highest incidence of infected students was precisely among those who sat in the front rows in front of the teacher (see below in the CDC chart).

Under current circumstances, Daniel Becker says, it is “inadmissible for a teacher not to wear a mask in the classroom”. “The politicization of the use of masks is stupid — that it is not possible to reach a consensus on something so simple”, he criticizes.

One point is that the infection in the California school occurred despite important sanitary measures being taken: the classrooms had their windows open and had high-efficiency air filters.

Despite this, ventilation in school environments remains a crucial measure to reduce the chances of virus transmission, by reducing the concentration of potentially infected droplets and aerosols (an expert suggestion is to place a fan facing a window – it works like a kind of exhaust fan, pulling the air from inside and pushing it out of the room).

Vaccination offered community protection

“This outbreak originating in an unvaccinated teacher demonstrates the importance of vaccinating school workers who are in close and indoor contact with children who cannot be vaccinated, as schools reopen their doors,” says the CDC study, highlighting the high scattering potential of the delta variant.

But the CDC also points out that the high vaccination rate in Marin County, where the school in question is located, has helped contain the coronavirus, offering collective protection:

“Transmission beyond (from students and family members) appears to have been impeded by high levels of community vaccination. At the time of the outbreak, about 72% of the population for which vaccine was available was fully vaccinated,” the study says.

“These findings support the evidence that current FDA-approved emergency covid-19 vaccines are effective against the delta variant. However, transmission risks remain high among unvaccinated individuals in schools “, the text continues.

The CDC emphasizes that, in addition to mass vaccination, it is necessary to maintain strict prevention measures — correct use of masks, routine testing, constant ventilation and quarantine in the case of symptomatic people or those who tested positive — to ensure protection in the school environment.

In the US, after the mass vaccination campaign placed the country at the forefront of global protection against covid-19, the resistance of part of the population to immunization created fertile ground for the delta variant to spread in some communities.

This resistance also caused the US to reduce the rate of immunization of the general population. According to Oxford University’s Our World in Data platform, as of September 12, around 178.7 million Americans were fully vaccinated, out of a total population of 328 million people.

Currently, while Brazil applies 0.66 daily doses of vaccine per 100 inhabitants, in the US this rate is currently 0.22.

This led to measures such as the one adopted in Los Angeles County, also in California, where vaccination of all students aged 12 and over became mandatory, despite resistance on the part of parents – either because they did not feel safe or vaccine or for disagreeing with outside interference in decision-making with regard to children, Reuters reported.

But, in the words of one of the school board members (in whose instance the mandatory vaccinations were approved), “I don’t see it (vaccination) as your choice or my choice. I see it as a community need. Which means people they will have to do things that they are not comfortable with, that they are unsure of, or that may contain some risk.”

adults have to protect children

Finally, an important lesson from the CDC study is that adults are still responsible for ensuring that schools are safe places.

“Vaccines are effective against the delta variant, but the risk of transmission remains high among unvaccinated people in schools where there is no strict compliance with prevention strategies,” says the CDC.

For now, says pediatrician Becker, what we do know is that, as the delta variant is more transmissible, it also transmits more among children, at the same rate (that is, even in lower absolute numbers than among adults).

In Rio de Janeiro, delta is considered the variant of the coronavirus prevalent in infections since last month, increasing the burden on hospitals. A recent analysis pointed out that this variant represents 90% of genetically sequenced cases in the state – and it is worth remembering that, at various times during the pandemic, the situation in Rio de Janeiro anticipated the general situation seen in the rest of the country.

“With Delta, we’re seeing children taking the virus home, which we haven’t seen so much before. But the vast majority of children continue to get covid-19 at home from adults,” says Becker.

This increase in delta contagion has not, at least for now, been reflected in more deaths among children, says the doctor.

“At this moment, there is no explosion of cases among children or reason for panic. But we have to strictly implement the protocols. It is not a time for parties in closed places, because the delta is really rough. We have to take care of the children, who are a group not yet vaccinated”, he concludes.