In Costa Rica, three respiratory viruses are currently circulating most, according to the Ministry of Health. During the last week, the entity reported the presence of seven viruses in the country, but the ones causing the most illness are rhinovirus, COVID-19, and influenza A.
Juan José Romero, an epidemiologist at the National University (UNA), explained the behavior of these viruses: “During the first months of the year, we usually see fewer severe acute respiratory infections compared to May and June, when hospital saturations occur,” he noted.
Factors such as decreased rainfall, increased wind, and high temperatures reduce the number of people spending time in closed spaces, which reduces the risk of contagion between sick and healthy people.
“The types of viruses and bacteria that circulate vary throughout the year, so there is no clear and conclusive explanation as to why rhinovirus predominates at a certain time, followed by syncytial virus, or others,” Romero added.
Symptoms
According to the expert, the three infections present similar symptoms. Fever, for example, can manifest with any of the three viruses. “Some cases may present with cold-like symptoms, affecting the upper respiratory system: nose, back of the mouth, and throat,” he indicated.
“When the middle or lower respiratory tract is involved, the symptoms are more severe, such as a persistent cough, difficulty breathing, and problems with oxygen exchange. In these cases, it is necessary to see a doctor instead of self-medicating with over-the-counter medications,” he recommended.
Rhinovirus
The common cold is primarily caused by rhinovirus and is characterized by symptoms such as:
Nasal congestion or runny nose
Sore throat
Cough
Sneezing
Mild headaches
Malaise
These symptoms are usually mild, and people generally recover within 7 to 10 days.
However, in 2024, rhinovirus was the virus that caused the most deaths in children, accounting for 18 of the 50 deaths reported by the National Children’s Hospital. Although it usually causes mild upper respiratory infections, it can be more severe in people with asthma or chronic lung disease.
COVID-19
COVID-19 is a respiratory illness caused by the SARS-CoV-2 coronavirus. Its symptoms can vary, but the most common include:
Fever or chills
Cough
Shortness of breath (dyspnea)
Fatigue
Muscle or body aches
Headache
Loss of taste or smell
Sore throat
Nasal congestion or runny nose
Nausea or vomiting
Diarrhea
Symptoms may appear 2 to 14 days after exposure to the virus.
Although cases have decreased compared to the pandemic, COVID-19 continues to cause hospitalizations and deaths. In fact, the Ministry of Health has already reported the first two deaths of 2025. To prevent severe cases, vaccination remains a key tool, as it helps reduce the intensity of symptoms.
Influenza A
Influenza A is a flu virus that causes acute respiratory infections. Its symptoms usually appear suddenly and include:
High fever
Cough (usually dry)
Sore throat
Muscle and joint aches
Severe headache
Severe malaise
Nasal congestion
Every year, the Costa Rican Social Security Fund (CCSS) administers the seasonal influenza vaccine, prioritizing at-risk groups, who are the most vulnerable to the disease.
Young children, older adults, and people with comorbidities can develop severe symptoms requiring hospitalization and even leading to death. In 2024, only 29% of children between 6 months and 8 years of age received the vaccine. That same year, the National Children’s Hospital reported six deaths from influenza A.
Recommendations:
Some of these infections can be prevented with vaccination, so it is essential to administer them to at-risk groups.
Other ways to strengthen the immune system include:
Maintaining a balanced diet
Getting enough sleep
Getting regular physical activity
“Exercise is key to strengthening the immune system. Children should run and play, while adults should get at least 30 minutes of physical activity daily,” Romero recommended.
In addition, with the start of the school year, it is important that children and adolescents with symptoms of illness stay home from school to avoid outbreaks and the spread of these viruses in educational centers.
