Every day there are new infections. With three consecutive weeks reporting more than a thousand new cases, Venezuela is going through the expansion stage or exponential phase of the COVID-19 epidemic. The new case curve continues its rise. What does this mean?
The epidemic widening phase occurs when there is a sustained outbreak of the disease in the community and threatens to continue expanding, according to the Glossary on outbreaks and epidemics of the Pan American Health Organization (OPS).
Tulia Hernández, an epidemiologist and PAHO adviser in Venezuela, explains that this is the normal course of the spread of an infectious disease. Its speed depends on the characteristics of the virus: how easy it is to transmit, how virulent or how capable it is of causing disease, and what characteristics its host has.
“It is the natural behavior of the evolution of an epidemic by an infectious disease that is transmitted from person to person. It means that the number of cases that occur is increasing and doubling each period studied, which can be days, “she says.
Saúl Peña, health officer and president of the Venezuelan Society of Public Health (Svsp), indicates that it means that there is a sustained increase in the number of people infected, which is known as morbidity. It highlights that there is currently a significant increase in the number of cases of COVID-19 by community transmission.
For Hernández, this stage may have occurred earlier, after the announcement of the first cases. However, early quarantine, fear of disease, and even gasoline shortages, which limited internal mobility, contributed to delaying the start of the exponential phase. Now, with a flexibility scheme and even without a vaccine, the rise of the curve can only be stopped in two ways: with more barrier measures or after a percentage of the population has become ill.
When is the peak of the curve reached?
The development of an epidemic can be represented by epidemic curves: the graphic expression of the frequencies or the number of new daily, weekly or monthly cases of the disease.
The epidemic curve it always has three elements: the rising curve, which represents the increasing phase of the epidemic; the peak, peak or plateau, which can be reached naturally or stopped by an intervention, and the downward curve, which represents the depletion phase of the epidemic, which can be natural or caused.
The Venezuelan Public Health Society estimates that the exponential phase, with an ascending curve, it will remain at least throughout the month of July.
Epidemiologist Tulia Hernández highlights that it is not possible to state precisely when the peak of the curve will be reached, the stage with the most new cases. There are mathematical models to predict when it might occur, but he notes that they are not exact.
Stresses that most of the models from Venezuela agree that the period with the highest number of cases would occur between June and September. Maybe a decline can begin after those months, but experts don’t know if the exponential phase will extend.
“There is no precise time, and less with this. We are seeing that the curve is going up, which are increasing cases every week. When these cases begin to go down, to reverse the path, because people comply more with the measures, because there is a vaccine or because people have already suffered the infection, we will see that the cases begin to decrease and we will be able to say when the peak exactly ”, says Hernández.
But another element enters the equation: still how long immunity lasts unknown generated by the virus. To consider that there is herd or herd immunity, 60 to 70% of the population that has been in contact with the virus and developed antibodies must be reached.
“It has not yet been totally ruled out that there may be reinfecciones. That someone, for example, has a mild infection, is mildly asymptomatic, their antibodies are short-lived and at the end of the year they can have a reinfection ”, adds the epidemiologist.
When will the epidemic be controlled?
The president of the Venezuelan Public Health Society (Svsp) indicates that in order to consider that the epidemic of COVID-19 is controlled, a fall in the epidemic curve must be observed with a significant decline of the number of infected and the number of deceased.
In addition, he says, there must be an increase in the number of recovered. It will be at that time, when there is a sustained decrease in the number of cases, when the quarantine can be abandoned.
What should people do during the exponential phase? Experts recommend that the same measures applied so far be maintained: prevention and containment.
“The only thing that has resulted is staying at home, washing your hands frequently, using antibacterial and using your face mask, which covers your nose and mouth,” says epidemiologist Tulia Hernández.
Staying at home and not going out on the street if it is not necessary, maintaining hygiene, protecting yourself when you have to go out and maintaining physical distance in the street and commercial premises are the recommendations to prevent infections, highlights Dr. Saúl Peña.
–
