COVID-19 diagnosis: Rapid Test or Polymerase Chain Reaction?

In early 2020, the first time in Wuhan, China, SARS-COV-2 infection which manifested clinically as COVID-19 had become a threat to the health of the world community. This disease is very easy to spread and is infectious, which in March 2020, the World Health Organization has made Covid-19 infection status a global pandemic. No less than 200 countries have contracted this infection in both developed and developing countries. Although currently, more than 10 million people are infected with Covid-19, statistically the mortality rate is still around 5-6% worldwide. Unlike the SARS or MERS disease that occurred in 2003, this SARS-COV-2 infection is more easily spread by local transmission due to exposure to droplets containing this virus. The high number of infections and mortality rates in vulnerable populations (old age, weak immune system, and the presence of comorbidities such as diabetes, respiratory system, etc.) direct many countries make efforts to prevent the spread of Covid-19 infections occur through social distancing, self-isolation, quarantine, lockdown, or as in Indonesia with the implementation of Large-Scale Social Restrictions (PSBB). However, these policies are unlikely to be effective without supporting examinations to confirm the presence of Covid-19 infection in the population. In this regard, an examination that has high sensitivity and specificity in the diagnosis of Covid-19 diagnosis is fundamental so that the actions of each country's government to carry out quarantine of its citizens can run optimally.

The diagnosis of COVID-19 has been systematically compiled by WHO and other world health experts so that it can be used as a joint guideline. In establishing the diagnosis, the clinician will always be guided by the history, examination of clinical symptoms, to the use of supporting examinations. Like corona type virus infections in general, flu-like syndrome symptoms are the most prominent things such as fever, runny nose, shortness of breath, and cough. These non-specific clinical symptoms make the clinician have to use a supporting examination in confirming the diagnosis of Covid-19 which has now been agreed that the examination of the Rapid Test and Polymerase Chain Reaction (PCR) in establishing the diagnosis.

The fundamental difference from the Rapid Test compared to PCR is the inspection method that will be performed. In the Rapid Test, the principle of the interaction of antigen and antibody bonds is assessed in this examination. Rapid Tests will use the patient's blood plasma to evaluate whether there is a positive bond between the specific antibody of the SARS-COV-2 virus and the antigen present in the examination kit reagent. Interpretation of results can be either positive/reactive and negative/non-reactive in some reagent kits that will provide information on binding antibody types such as immunoglobulin-M (IgM) or immunoglobulin-G (IgG). Simply interpreted the results given can indicate an infection that is acute if there is a positive result on the IgM assessment or the infection has entered the convalescent stage if found positive results on IgG. However, this rapid test has several disadvantages, where the false-positive rate is quite high, which is related to the time of examination. This is because antibodies in patients infected with Covid-19 only begin to form on days 7 to 10 after infection so that negative results at the first examination do not negate the possibility of no infection in patients. While positive examination results do not indicate that the patient is still infectious where the presence of Covid-19 specific antibodies will still circulate in the body for the next few weeks. In this regard, a re-examination is necessary if the first examination is found to be a negative result and a confirmation check with PCR is carried out if the PCR results are reactive.

Polymerase Chain Reaction (PCR) examination is the gold standard in Covid-19 diagnosis. This is because the SARS-COV-2 viral RNA genetic material is specific so that positive results are sufficient to confirm the presence of Covid-19 infection in patients. However, PCR examination is relatively more complicated where the process requires laboratories with a minimum level of Biosafety Level-2 (BSL-2), trained staff, more expensive costs, level 3 personal protection equipment (APD Level 3), and it takes some time days before results can be obtained.

In order to diagnose Covid-19, the Rapid Test and PCR examination cannot be separated from one another. In a large population, where screening efforts need to be carried out, the Rapid Test examination can be considered the most appropriate given the easy workability, fast results, and can reach the wider community. However, as an effort to confirm the diagnosis and see the response of therapy given, PCR examination is the primary choice as a gold standard based on WHO criteria. Based on the mentioned above, the community could understand simply the differences and the functions of the Rapid Test and PCR in establishing the diagnosis of Covid-19.