The Ministry of Health has denounced a Trinidad Express editorial as ‘misinformation’ after the newspaper criticised the government for not testing people who were in contact with Prime Minister Dr Keith Rowley during the two weeks prior to his positive test for Covid-19.
The editorial, which was published today, quoted the World Health Organisation (WHO) to describe the incubation period for Covid-19 as ‘the time between exposure to the virus and symptom onset’, which ‘is on average five to six days, however, it can be up to 14 days. During this period, also known as the pre-symptomatic period, some infected persons can be contagious.’
The Express contended that since the virus could be transmitted up to 14 days prior to the onset of symptoms, anyone in contact with the prime minister during that time should have been tested.
‘Knowing that Dr Rowley was physically at parliament on 26 March, 11 days before exhibiting symptoms, which was well within the 14-day pre-symptomatic period,’ stated the editorial, ‘the speaker and the managers at parliament should have immediately informed all MPs, staff and others who were present.
‘Even if no one felt threatened, everyone should have been tested, and the premises evacuated for sanitising before the resumption of work and parliamentary sittings. The same goes for any other group of persons exposed to him during that period.’
However, the Ministry of Health claimed that the Express editorial board got the science wrong. In its statement, the ministry said there is a difference between the virus’ incubation period (the time it takes someone to show symptoms) and the infectious period (the time within the incubation period when someone can transmit the virus to another person).
The ministry’s release stated: ‘The science indicates that Covid-19 infection only begins to be transmissible from one person to another from two days before onset of symptoms, and does not span the entire incubation period, as posited by the editorial. This biological fact guides the contact tracing protocols currently in force worldwide, in line with the guidance of the World Health Organisation (WHO).’
The ministry went on to say that contact tracing protocols were linked to the infectious period of the disease—in this case two days before the appearance of symptoms.
‘For Covid-19, in particular, the period for pre-symptomatic transmission has been defined and accepted by WHO and Centers for Disease Control and Prevention (CDC) as two days before symptom onset—the fact which guides the contact tracing guidance elaborated by both the WHO and CDC websites,’ the release stated.
The WHO’s February 2021 guidelines for contact tracing reads: ‘Exposure must have occurred during the infectious period of the case, and defined as follows:
‘Exposure to a symptomatic case: 2 days before and 10 days after symptom onset of the case, plus at least 3 additional days without symptoms (including without fever and without respiratory symptoms), for a minimum of 13 days total after symptom onset.’
The Ministry of Health’s complete press release appears below:
The Ministry of Health notes with concern the misinformation reported in the Editorial in today’s Express newspaper as it relates to the contact tracing protocol for Covid-19 positive cases. Unfortunately, the article is based on incorrect assumptions that are not scientifically accurate and the conclusions are therefore flawed.
The Ministry hereby provides a clarification of the science that forms the basis of the national contact tracing protocols.
An individual can be infected by a virus and may take several days to show symptoms – the incubation period.
Within the incubation period, a person may begin to be able to infect other people a few days before symptoms start to show – the infectious or communicable period.
There is a clear difference between the incubation period for COVID-19 and the duration of time during which someone is likely to transmit this virus.
For Covid-19, the incubation period is documented to extend up to 14 days.
The science indicates that Covid-19 infection only begins to be transmissible from one person to another from two days before onset of symptoms, and does not span the entire incubation period, as posited by the editorial. This biological fact guides the contact tracing protocols currently in force worldwide, in line with the guidance of the World Health Organisation (WHO).
The editorial inaccurately disassociates the science of the communicability of a disease from the relevant contact tracing activities. It stands to reason that the contact tracing protocol must be closely linked to the infectious period for any disease, including Covid-19.
The formal definitions of the periods in question, and references for contact tracing guidance are listed below:
Last’s Dictionary of Epidemiology1 defines the INCUBATION PERIOD for an infectious disease as: The time interval between invasion by an infectious agent and appearance of the first sign or symptom of the disease in question.
For COVID-19 the incubation period ranges from 2 to 14 days
Last’s Dictionary of Epidemiology defines the COMMUNICABLE PERIOD for an infectious disease as: The time during which an infectious agent may be transferred directly or indirectly from an infected person to another person…
For some diseases, e.g. measles, influenza, chickenpox, persons can be infectious for a period before onset of symptoms (the pre-symptomatic period). This period varies from one disease to another
For COVID-19, in particular, the period for pre-symptomatic transmission has been defined and accepted by WHO and Centers for Disease Control and Prevention (CDC) as 2 days before symptom onset – the fact which guides the contact tracing guidance elaborated by both the WHO and CDC websites (See links and excerpts below.)
CDC Guidance on Contact Elicitation: available from: https://www.cdc.gov/coronavirus/2019-ncov/php/contact-tracing/contact-tracing-plan/investigating-covid-19-case.html#anchor_15900
“…Determining the contact elicitation window: When interviewing a symptomatic client, a case investigator should elicit all close contacts from 2 days prior to onset of any symptoms through the beginning of isolation…”
WHO Guidance on Contact Elicitation: available from: https://www.who.int/publications/i/item/contact-tracing-in-the-context-of-covid-19
“…Exposure must have occurred during the infectious period of the case and defined as follows: Exposure to a symptomatic case [between] 2 days before and 10 days after symptom onset of the case…”
It is hoped that this information addresses any misconception on the matter. The Ministry of Health will continue to be guided by the science as it seeks to safeguard the health of the Trinidad and Tobago population.