COVID-19 Community Spread & Contact Tracing

As cases of COVID-19 increase across Trinidad and Tobago, we frequently hear differentiators amongst the types of cases, with little explanation of the types.

What is an Imported Case?

According to the World Health Organization (WHO), imported cases are considered cases that are acquired outside of the location that is reporting. In Trinidad and Tobago’s case, this means that COVID-19 would have been acquired outside of the country’s borders and was confirmed by testing within the country.

What is Community Spread (Transmission)?

The key point in the definition of community spread or community transmission is that the source of infection is unknown.

Community spread or community transmission is defined by the United States Center for Disease Control (CDC) as people being infected with the virus in an area, including some who are not sure how or where they became infected.

According to the WHO, community spread or transmission is evidenced by the inability to relate confirmed cases through chains of transmission for a large number of cases, or by increasing positive tests through sentinel samples (routine systematic testing of respiratory samples from established laboratories). In T&T’s case, this will be systematic testing by CARPHA or (soon) the Eric Williams Medical Sciences Complex.

Reiterating: Community transmission or community spread are areas that are experiencing larger outbreaks of local transmission defined through an assessment of factors including, but not limited to:

  • Large numbers of cases not linkable to transmission chains
  • Large numbers of cases from sentinel lab surveillance
  • Multiple unrelated clusters in several areas of the country/territory/area.

What is Local Transmission?

Simply, local transmission or local spread, based on the WHO definition, occurs when the source of the virus is within our borders. This can occur when an imported case infects a primary contact or that primary contact infects a secondary contact.

What is Contact Tracing?

Primary Contact: Primary contacts are the first set of people the patient comes into contact with, usually family members.

Secondary Contact: If a primary contact goes to school, work, church, or any other location outside of the home, and the virus is transmitted to someone at those locations, they are referred to as secondary contacts.

Tertiary Contact: People who interact with secondary contacts and contract the disease are known as tertiary contacts.

Speaking at a media briefing on Tuesday, a medical epidemiologist at the Ministry of Health, Dr. Avery Hinds explained the terms used within contact tracing and how it is conducted.

Dr Hinds said contact tracing is carried out initially by reaching out to primary contacts to find out who might have been exposed.

“We identify persons who were potentially exposed and people who were confirmed with COVID-19. We ask those individuals with whom they’ve been in contact.”

“Initial people they would have been in contact with are usually family members who are primary contacts. Those primary contacts are asked to quarantine at home.”

“We then follow up with these persons to find out whether during the course of their exposure, subsequent to the exposure during the course of what we call the incubation period, the 14-day period, whether they developed any symptoms.”

“If they become symptomatic then they’re followed up to get testing and medical management.”

Dr Hinds said the Ministry also reaches out to potential secondary contacts.

“Our medical systems are geared toward making calls to the people with whom a potential case may have been in contact and notifying them that they may have been exposed.”

Dr Hinds said those people are advised to self-isolate at home and monitored to see if symptoms develop.

He said the measure to ask everyone to limit gatherings is one of precaution.

“The reason we’re asking people outside of these gatherings to limit their movement is that although we know not every cough is a COVID-19 case, we are acting on a precautionary principle.”

He said technology is used to create geo-locations of these contacts for analysis to see where they are likely to move around. 

“We map the patients and contacts, we can visualise the change of transmission…and hot spots.”

He said understanding the geographic locations of this data can help them to decide where to allocate resources.

What to do if you think you have COVID-19?

If you have traveled to or had close contact with someone who traveled to a country where COVID-19 was present and/or develops a fever, dry cough, shortness of breath or breathing difficulties and/or acute diarrhea, do the following:

  1. If you develop a mild cough of low-grade fever (temperature of 37.3 degrees Celcius or more), stay at home and self-isolate. Avoid close contact with family members.
  2. Contact your area health center, giving them details of your recent travel or exposure and the symptoms you’re experiencing.
  3. Do avoid visiting private institutions and doctors’ offices.
Call for advice regarding suspected cases of COVID-19 from the Ministry of Health
Call for advice regarding suspected cases of COVID-19 from the Ministry of Health

In Trinidad, you can also call the COVID-19 hotline, 877-WELL (9355). In Tobago, anyone suffering from flu-like symptoms can call 211 for help. Remember, if it is an emergency, call 811 for ambulance services.

Following contact with the Ministry of Health, officers will visit your home for the following:

  • To have samples taken from you for the confirmation of the virus (which will be tested by CARPHA).
  • To assess your symptoms and recommend medication safe to have. It is best to avoid aspirin or aspirin based medication until you are assessed.
  • Arrange transfer to a hospital facility if your condition requires supportive care and management.

What are the criteria for testing?

According to statements in a press conference on March 20th, 2020, the Caribbean Public Health Agency (CARPHA) has widened capacity to test.

“We are now using the new definitions from the WHO guidelines which now indicate all samples that are meeting the definition for a suspect or probable case of COVID-19 will be tested from all CARPHA member states.” Dr. Lisa Indar, Assistant Director CARPHA

Suspect Case:

  • A patient with acute respiratory illness (fever and at least one sign/symptom of respiratory disease, e.g., cough, shortness of breath), AND a history of travel to or residence in a location reporting community transmission of COVID-19 disease during the 14 days prior to symptom onset; OR
  • A patient with any acute respiratory illness AND having been in contact with a confirmed or probable COVID-19 case (see definition of contact) in the last 14 days prior to symptom onset; OR
  • A patient with severe acute respiratory illness (fever and at least one sign/symptom of respiratory disease, e.g., cough, shortness of breath; AND requiring hospitalization) AND in the absence of an alternative diagnosis that fully explains the clinical presentation.

Probable Case:

  • A suspect case for whom testing for the COVID-19 virus is inconclusive (result from the testing laboratory). OR
  • A suspect case for whom testing could not be performed for any reason.

However, even if you meet these case definitions, CARPHA may still reject your swab for testing. According to Dr. Roshan Parasram in a Post-Cabinet Briefing on March 19th, 2020, “Testing should be done from day zero to day five from the onset of symptoms. If we go beyond day five, day six,  seven or day eight, they will possibly not take the test or not do the test even if we send the sample. And if its less than zero, meaning you have no symptoms, the test will not be done.”

Based on the latest laboratory guidance from CARPHA as of March 20th 2020, that requirement remains. Results may take 24-48 hours.

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