QCOSTARICA – The rate of vaccination against covid-19 got a big boost a few weeks ago with the arrival of more than 750,000 vaccines in one week, the majority, 500,000 doses donated by the United States.
In the last week, however, vaccination dropped to a daily average, 32,912 doses, 39.5% lower than in the previous seven days, increased again the time to achieve the longed-for herd immunity, which is when 80% of the population has been inoculated against the SARS-CoV-2 virus.
If it average rate of 32,912 daily vaccinations maintains, Costa Rica would reach the goal in just under five months, at the end of December, in about 147 days.
A week ago, the country was three months away (93 days) and two weeks ago, just over six (185 days).
This new increase in the term is due to the fact that, between Tuesday, July 27 and Monday, August 2, the Caja Costarricense de Seguro Social (CCSS) reduced the number of injections applied between one week, lowering the daily average from 54,443 to 32,912.
The week between Tuesday, July 20 and Monday, July 26, 331,100 people were vaccinated people, 61% more than the previous week (206,004 doses applied) and, 290% more than the 84,996 applied during the week between Tuesday, July 13 and Monday, July 19.
Three weeks ago, the threshold to achieve herd immunity was raised from 70% to 80% of the vaccinated population, following the recommendation of the demographer and public health worker Luis Rosero Bixby, when considering the arrival of the delta variable of Covid-19, which is much more contagious and could increase the number of hospitalized patients and deaths, as has happened in other countries and currently happening in Costa Rica.
In the last two days (August 4 and 5), the number of infections once again rose, almost 2,000 each day, as did deaths and hospitalizations.
On Wednesday, August 4, there were 1,795 new infections and 17 deaths, while on Thursday, August 5, the Ministry of Health reported 1,827 new infections and 21 deaths. We hadn’t seen these numbers since the last week in June.
As to hospitalizations, the latest figures by the Caja indicate 851 patients in hospital, of which 380 are in an Intensive Care Unit (ICU), above what is considered for optimal care.
Back to vaccinations, the figures only consider people vaccinated in Costa Rica by the Caja and do not include those who injected themselves abroad, whose data has not been disclosed.
Nor does it include immunity generated by the virus or the possible infections that may occur in people already inoculated.
Country situation
Data from the CCSS, updated as of this Monday, August 2, indicate that 3,424,278 doses have been applied, of which 2,573,189 (49.84% of the population) have received the first dose and 851,089 people (16.48% of the population) already have the complete scheme with two doses.
The total population projections by the CCSS is 5,163,021; the target population to be vaccinated from 12 to more than 100 years is 4,274,344 (83% of the total population).
Currently, the second dose is applied three weeks (21 days) after the first, in those over 58 years of age and in pregnant women, and 12 after the first in the rest of the population.
By age, the most advanced group is 58 years and over, where 714,325 people (87% of the age group) have already received both doses; 4% are waiting for the second dose. The remaining 9% have yet to be vaccinated or have been vaccinated outside the country and there is still no data to determine the number.
In the 40-57 age group, 70% have at least one dose. 6% already have both.
In the group aged 20 to 39 years, 49% have already received their first vaccine and 4% have the second. A large part of these people are part of the group of workers on the first line of care for the pandemic.
Finally, in the 12 to 19 age group 33% of people have already started their immunization. In this population, 1,111 second doses have been applied.
Herd immunity
In short, it is a large number of people (the herd) immunized against a virus, who will protect those who are not immunized.
There are two ways to acquire it. By vaccines or by the so-called natural immunity.
How to achieve this immunity with vaccination
As people begin to receive vaccines, they generate antibodies and defense cells against the virus, so that, if they come into contact with it, the immune system recognizes it and does not make them sick (or it does it in a much milder way). These people would be less likely to infect someone else.
At any given time, so many people will have antibodies against the virus that its circulation would be less active, so this would protect the population that has not been exposed.
This does not mean that the disease will be eliminated; the virus will always remain to some extent, but not at the level of an epidemic.
There is no exact number of people who must be vaccinated to say “from now on, the goal has been reached.” For this reason, thresholds are used in which protection to the community could oscillate.
With SARS-CoV-2, the virus that causes covid-19, several thresholds have been managed. For this, we talk about herd immunity when the country and each health area have reached 80%, 85% or 90% of people vaccinated with two doses.
Why? At first, 60% or 70% was talked about to reach this point. However, as the virus, its forms of transmission and human dynamics became better known and more contagious variants appeared, such as delta, the percentage necessary to achieve mass immunization increased.
Vaccines are not 100% effective. There are people who, even with the complete vaccination scheme, could become infected and transmit the disease to other people. Having a fully vaccinated population does not eliminate the disease.
Natural immunity
It is acquired when a person acquires the infection. When a person recovers from the virus, they maintain antibodies that they would prevent for a time from being contagious and infecting someone else and this would also bring closer to herd immunity
According to the Johns Hopkins, if you’ve been infected, you have some protection. But that immunity has limits. The biggest limit is that it doesn’t last as long as we would like it to.
Immunity from natural infection starts to decline after 6 to 8 months. We know that fully vaccinated people still have good immunity after a year—and probably longer.
With infection, you don’t know how bad it’s going to be. By not getting vaccinated, you’re rolling the dice. You may become severely ill. You may have to be hospitalized. You may die. There’s also the risk of long COVID.
