LUZON has been under quarantine for more than a month now while localized quarantine measures have been imposed for the past three weeks in several local government units (LGUs) in the Visayas and Mindanao in an attempt to stop the spread of the novel coronavirus, or Sars-CoV-2.
This new coronavirus, which the US Centers for Disease Control and Prevention (CDC) said is spreading more efficiently than influenza, causes a respiratory infection called coronavirus disease 2019 (Covid-19), which the World Health Organization (WHO) described as more infectious than the severe acute respiratory syndrome (Sars).
Less than three months after first wreaking havoc in China, the virus also forced other countries to close their borders and place entire regions, cities and provinces on lockdown.
Travel and tourism have ground to a halt, other economic activities have been restricted while governments have been scrambling for funds to bolster public health systems and provide fiscal and monetary relief to affected citizens.
To understand this unseen enemy better, SunStar Philippines has put together a primer on often-used terms and major developments in the struggle to contain the pandemic.
Virus
A virus is a microscopic and infectious biological entity that is surrounded by a protective coat of protein called a capsid, according to the Microbiology Society in Europe.
In some viruses, like the coronavirus, the capsid is surrounded by crown-like spikes called the envelope.
A virus is so small “that 500 million rhinoviruses (which cause the common cold) could fit on to the head of a pin.”
Its genetic material is either a DNA (deoxyribonucleic acid), the two-strand molecule that stores genetic information in all organisms, or RNA (ribonucleic acid), a one-strand molecule synthesized from DNA.
On its own, a virus is inert and is considered a non-living thing. It cannot move. It cannot travel or spread on its own. It cannot do anything.
It is able to multiply only when it enters a living cell, called the host cell.
Coronavirus
The virus causing the current pandemic is a coronavirus, which is known to cause the common cold and other respiratory infections in humans such as the Sars in 2003 and the Middle East respiratory syndrome (Mers) in 2012.
The World Health Organization (WHO) was informed on December 31, 2019 of a cluster of cases of pneumonia caused by a mysterious virus in Wuhan City in Hubei province in central China.
The mysterious virus was later discovered to be another zoonotic coronavirus that was transmitted from animals to humans.
This one is believed to have originated from bats. How it was transmitted to humans is not clear, the WHO said.
“Bats are rare in markets in China but hunted and sold directly to restaurants for food. The current most likely hypothesis is that an intermediary host animal has played a role in the transmission,” the WHO said in its situation report on February 11, 2020.
Sars-CoV-2
This coronavirus was initially identified by Chinese scientists as the novel coronavirus, or 2019-nCoV.
It was later given the name "severe acute respiratory syndrome coronavirus 2" (Sars-CoV-2) by the International Committee on Taxonomy of Viruses (ICTV), the global body responsible for designating and naming of the virus taxa (phylum, order, family, genus, or species).
The ICTV Coronaviridae Study Group, which is composed of experts on coronaviruses, had determined that Sars-CoV-2 belongs to the existing species, Severe acute respiratory syndrome-related coronavirus. (A species name is always in italics and the first word begins with a capital letter.
The first Sars-CoV was the virus that caused the Sars outbreak and killed 813 people from November 2002 to July 2003. A total of 8,437 people were infected.
Covid-19
The WHO, which is responsible for naming diseases, had simply added acute respiratory disease, or ARD, to 2019-nCoV to identify the infection that the novel coronavirus causes. Initially, the disease was called 2019-nCoV ARD.
On February 11, 2020, the WHO announced that it has named the disease Covid-19, which is short for coronavirus disease 2019. The “19” is short for 2019, when the virus was first reported, and does not refer to the strain or genotype of the virus.
By then, the novel coronavirus had infected 43,103 persons -- 42,708 in China and 395 in 24 other countries. The number of mortalities had just breached the 1,000 mark.
Patient No. 2 in the Philippines, a visiting Chinese man, was recorded as the first mortality outside China. The rest, or 1017, died in China.
READ: Chinese man with nCoV dies in Manila hospital
As of April 22, infections have exceed 2.47 million worldwide, according to the WHO. Deaths have reached 169,006 in 213 countries.
In the Philippines, total cases reached 6,710 as of 4 p.m. April 22, including 446 mortalities and 693 patients who have recovered from the disease.
More infectious
The WHO said this new virus is more infectious than the first Sars-CoV, while the disease Sars is more deadly than Covid-19.
A peer-reviewed paper by a research team in Germany, which was published online on Nature on April 1, 2020, said the first Sars-CoV directly attacks the lungs and is more difficult to transmit.
The novel coronavirus, on the other hand, is easily spread because it actively replicates while still in the throat during the first week of infection, when symptoms are still mild and the patient is not even aware of being sick.
"This means that the novel coronavirus does not have to travel to the lungs to replicate. It can replicate while still in the throat, which means it is very easy to transmit," Professor Christian Drosten, a professor at the Berlin Institute of Health and a member of the research team, said in an interview with Science Daily.
"A high viral load in the throat at the very onset of symptoms suggests that individuals with Covid-19 are infectious very early on, potentially before they are even aware of being ill," Colonel PD Dr. Roman Wölfel, Director of the Bundeswehr Institute of Microbiology and one of the study's first authors, explained further.
When the novel coronavirus reaches the lungs, Covid-19 then resembles Sars and causes severe pneumonia, which could lead to death.
How the virus is spread
Both the WHO and CDC said the virus is transmitted through respiratory droplets that are produced when an infected person coughs, sneezes or talks.
These droplets can land in the mouths or noses of people who are within about six feet (nearly two meters) or possibly be inhaled into the lungs, according to the CDC.
It may also be contracted when a person touches a contaminated surface or object and proceeds to touch his or her mouth, nose or eyes.
The WHO said surfaces in the immediate environment of an infected person are likely contaminated as are objects used on the patient such as stethoscopes and thermometers.
A study by US scientists found that the virus is stable for several hours to three days in aerosols and on surfaces.
Sars-CoV-2 may be detected in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel.
The study was conducted by the US National Institutes of Health, CDC, UCLA and Princeton University scientists. It was published in The New England Journal of Medicine in March.
The WHO also said airborne transmission may be possible in specific circumstances and settings in which procedures or support treatments that generate aerosols are performed; i.e., endotracheal intubation, bronchoscopy, open suctioning, administration of nebulized treatment, manual ventilation before intubation, turning the patient to the prone position, disconnecting the patient from the ventilator, non-invasive positive-pressure ventilation, tracheostomy, and cardiopulmonary resuscitation.
Recent research also suggested that the virus may be spread by infected people with no symptoms.
Incubation period
According to the WHO, the incubation period -- or the time between catching the virus and developing symptoms of Covid-19 -- ranges from one to 14 days.
The average is after five days of infection.
Symptoms
The WHO has listed the most common symptoms of Covid-19:
* Fever
* Tiredness
* Dry cough
Some patients also complained of:
* Body aches and pains
* Nasal congestion
* Runny nose
* Sore throat
* Diarrhea
The research team in Germany also reported loss of taste and loss of smell in four of their nine patients.
“These symptoms are usually mild and begin gradually. Some people become infected but don’t develop any symptoms and don't feel unwell,” the WHO said.
Around one out of every six people who develop symptoms becomes seriously ill and develops difficulty breathing, it added.
Adults 65 years and older as well as people of any age with underlying medical problems, such as hypertension, heart problem or diabetes, are more likely to develop serious illness.
When to seek medical attention? WHO lists the following warning signs:
* Trouble breathing
* Persistent pain or pressure in the chest
* New confusion or inability to arouse
* Bluish lips or face
Local transmission
The Department of Health (DOH) confirmed local transmission on March 7 after reporting the case of Patient No. 5, a 62-year-old man who frequented a Muslim prayer hall in Greenhills.
Patient No. 5 had no travel history. He infected his wife, 59 years old, who became Patient No. 6. Both had died.
With the confirmation of local transmission, President Rodrigo Duterte declared a state of public health emergency on March 8, 2020.
READ: Philippines under state of public health emergency
Community transmission
According to the CDC, community transmission or community spread means some people have been infected and it is not known how or where they became exposed to the virus.
Confirmed case
Based on the DOH classification, this refers to a patient who was found positive for the virus through a real-time RT-PCR (reverse transcription polymerase chain reaction) test conducted by any of the 17 certified laboratories for Covid-19 testing in the country, led by the Research Institute for Tropical Medicine.
From April 16 to 24, however, RITM was forced to scale down operations because more than 40 personnel had contracted the virus.
As of 4 p.m. April 22, DOH reported a total of 6,710 persons who have been found positive for the virus in the Philippines.
Of this number, 446 had died while 693 beat Covid-19.
ILI, SARI
ILI means influenza-like illness, or a suspected influenza case. This refers to a person who suddenly develops a fever with cough or sore throat.
SARI stands for severe acute respiratory infection. This refers to a person who meets the case definition for ILI as well as experiences shortness of breath or difficulty breathing. The patient is a suspect case of severe undiagnosed pneumonia or acute respiratory distress syndrome and requires hospitalization.
Suspect case
This refers to a person who has developed ILI or SARI, but has not been tested for Sars-CoV-2. This person may have had travel history or close contact with a probable or confirmed case of Covid-19.
Other suspect cases are patients experiencing respiratory symptoms who: are 60 years old and above; have other underlying medical issues; have a high-risk pregnancy; and are health workers.
Under the old DOH classification, a suspect case referred to a patient under investigation (PUI) who has not been tested. DOH announced the new classification on April 11.
Probable case
This refers to a person who has developed symptoms, whether mild, severe or critical, and who is awaiting test results or whose laboratory test results are still being validated.
Under the old DOH classification, a probable case referred to a patient under investigation (PUI) who is awaiting test results or whose laboratory test results are still being validated.
Outbreak, Epidemic, Pandemic
According to the CDC, an outbreak refers to the sudden increase in the number of cases of a disease in a certain area.
In the case of the novel coronavirus, which is a newly discovered infectious agent, DOH Secretary Francisco Duque III had said that just one case is already an outbreak.
Epidemic refers to the sudden increase in cases above the thresholds set by the DOH for a certain area.
A pandemic refers to an epidemic that has spread over several countries or continents, usually affecting a large number of people, the CDC said.
On January 30, 2020, the WHO declared the Covid-19 outbreak a Public Health Emergency of International Concern.
More than a month later, on March 11, 2020, the WHO declared Covid-19 a pandemic, as cases topped 118,000 in more than 110 countries.
RT-PCR test vs Rapid Antibody Test
The novel coronavirus, or Sars-CoV-2, is detected through a reverse transcription-polymerase chain reaction (RT-PCR) diagnostic test that is conducted on a nasopharyngeal swab taken from an individual.
A rapid antibody test merely detects the presence of antibodies in the blood extracted from an individual. Antibodies are proteins produced by man’s immune system to fight off foreign entities such as viruses.
This means the antibodies are produced when an individual is infected. But finding antibodies in an individual does not necessarily mean that the person has contracted the novel coronavirus, or Sars-CoV-2. It only means that the individual was or is infected.
DOH Undersecretary Maria Rosario Vergeire said “rapid tests do not confirm if a person is truly positive or negative, especially when he/she is asymptomatic.”
Only an RT-PCR test can detect the actual presence of the virus.
As of May 5, 2020, the Food and Drug Administration (FDA) in the Philippines has approved 38 RT-PCR test kits for commercial use.
The FDA has also approved 39 rapid antibody test kits with varying specifications as of May 8, 2020.
In an advisory on April 18, the FDA cited the importance of the “timing of the infection and the condition of the patient during the time of specimen collection.”
“The selection of the type of kit to be used is also dependent on the indication, the information the doctor wants to obtain, and the specifications of the kit. Interpretation must be done with caution and clinical correlation,” the agency stated.
The 16 rapid antibody test kits detect either of three types, or a combination of two: total antibody, IgG antibody and IgM antibody.
The total antibody signifies the collective response of the patient’s immune system. IgM antibodies represent response to a current or recent infection while IgG antibodies represent response from a past infection.
As of April 22, there are 17 certified laboratories nationwide led by the Research Institute for Tropical Medicine. They have a combined capacity of 2,659 to 5,338 tests per day.