For the first time since the beginning of the pandemic, a study of geographic seroprevalence of Covid-19 will be carried out in Puerto Rico, which will allow estimating the magnitude of the spread of the virus infection on the island and identifying the areas of the population that they require prevention strategies and implementation of rapid controls.
The study will begin this weekend and will be carried out through a modified Community Assessment for Response to Public Health Emergencies (Casper) survey. In addition, it will have a random sample of people in the seven regions of the Department of Health (DS) in 64 municipalities.
Dr. José F. Rodríguez Orengo, executive director of the Puerto Rico Public Health Trust, said that the information collected will serve to create education and intervention strategies in the different communities. He added that they expect to have the results in three weeks and then submit a report to Health, which will use the results to establish public policies.
As part of this survey, 1,617 homes are expected to be visited in different parts of the island and a little over 6,400 blood samples will be collected. However, it is important to highlight that the Casper Project will be carried out in two stages, based on the random selection of homes, within each of the seven Health regions.
The first stage will establish a baseline of seroprevalence in the population and will describe the sociodemographic profile of the positive and negative cases, as well as the geospatial distribution of Covid-19 cases. While, the second stage will be carried out three months after the first Casper, in the same population and the same survey will be carried out to establish a comparison of seroprevalence during this period.
“Seroprevalence is practically collecting blood samples from thousands of volunteers throughout Puerto Rico and this time we are not forgetting Vieques, so we will be going to Vieques to find out how many people have been infected with the virus because of it and who have had the Covid-19. It is called seroprevalence because the serum of the blood to make the analysis of the antibodies that detect that you were exposed to the virus, ”said Rodríguez Orengo.
He added that this will help to know how widespread the novel virus is in the different regions of the island and the information collected will serve to create intervention and education strategies in the communities. Rodríguez Orengo mentioned that this study is of great proportions, since it brings together a large number of epidemiologists, biostatistics, health professionals and scientists, as well as universities, state and federal agencies and private companies.
Meanwhile, the Secretary of Health, Lorenzo González Feliciano, added that Casper is a well-known platform. “The important thing is to know how Covid-19 is moving in Puerto Rico, particularly in communities and in homes.”
What is the Casper?
Epidemiologist Diego Zavala Zegarra explained that the Casper is a rapid community assessment that is usually applied in disaster situations. He mentioned that the Casper was implemented in Puerto Rico after Hurricane María and it has been a very useful experience for the DS, which has a team trained to carry out this kind of community surveys.
“However, for the pandemic the Casper has been modified because the Casper is only a household survey. But we have modified it, as in other states such as Hawaii and Georgia, where in addition to the survey, blood samples are obtained in homes and that is precisely what we are going to do. We are going to do seven simultaneous Casper: one in each of the seven health areas in Puerto Rico, ”Zavala added.
To carry out the study, more than 200 people with experience in community surveys have been recruited, who will be distributed in the seven Health areas with their respective coordinators. In that sense, Zavala said that they have worked in the last six months to build the logistics, so he considered that they are ready and eager to implement the project. The selected neighborhoods were chosen at random.
“We are going to have teams of three people who are going to visit some neighborhoods that we have randomly pre-selected. In this team there will be a leader, who will be in charge of arriving at the house, presenting the team that will be properly uniformed with vests, to have the consent of the adult in the house to participate in the study, “he said.
Once consent has been obtained, an interview will be conducted using an electronic or telephone format, maintaining social distancing in the same home. Meanwhile, the nurse will be in charge of obtaining up to four blood samples in that house.
“In general, the stopping of antibodies now, especially now against SARS-CoV-2, which is the virus that causes Covid-19 in the blood, its presence or its stopping indicates a probable infection in the recent past and helps us to understand how much the pandemic has spread in the population. So seroprevalence studies can provide an estimate of infection in the population, which would include people who have had a mild or asymptomatic infection or even those who had symptoms but were not tested, ”he said.
He added that it is estimated that for each detected case of Covid-19 there may be between five, eight or ten cases that are active with the disease. “This study will be able to give us an estimate by region and Puerto Rico in general and all this information obviously the DS will be able to use to evaluate and modify its strategies for managing the pandemic in Puerto Rico,” he said.
For her part, Lucy Crespo, the main executive officer of the Trust for Science, Technology and Research of Puerto Rico (FCTIPR), highlighted that this study has been carried out across various regions of the United States and other countries to know the percentage of the population that has been exposed to the virus. “We hope that everyone sees this project as a project of great importance and relevance and that they help us,” he said.