For Dentists: Coronavirus 19- What you need to know?
Updated: Mar 28, 2020
Please note that the updates regarding this outbreak are ongoing. Please always refer to your local Health Service, or state branch of the Australian Dental Association if you are a member.
What is the Coronavirus?
The word Coronavirus indicates a large family of viruses which belong to the family of Coronaviridae, of the order Nidovirales, and comprise of large, single, plus-stranded RNA as their genome. Several members of the Coronavirus family may cause mostly mild respiratory disease in humans; however, notable exceptions that have gained worldwide recognition include the Severe Acute Respiratory Syndrome (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV) in the early 2000s and again in 2013. These caused some patients to succumb to fatal severe respiratory diseases. Recently, the word coronavirus has been used to describe the β-coronavirus 2019-nCoV, also called the novel coronavirus (nCoV) or Covid19. This is the seventh member of the family of coronaviruses that infect humans, and a new strain that hasn’t been discovered in humans before. Like SARS-CoV and MERS-CoV, it belongs to the β-CoV. This virus is zoonotic, with Chinese horseshoe bats (Rhinolophus sinicus) being the most probable origin. From Wuhan, Hubei province in China, this virus has since spread around the world and the World Health Organization has declared a global pandemic. As of March 12 2020, 2019-nCoV has been recognized in 52 countries, with a total of 125 048 confirmed cases and 4613 deaths.
Emerging evidence suggests the 2019-nCoV mutations may lead to different strains which predominate in geographical locations. For example, the strain in Italy is thought to be more virulent as compared to the one in Australia, which evolved from the original in Wuhan.
How is it spread?
It is thought to be passed directly from person to person by aerosolised particles and respiratory droplets, as well as contact transmission, such as the direct contact with oral, nasal, and eye mucous membranes after touching contaminated surfaces. Whether it can be spread through aerosols or vertical transmission (from mothers to their newborns) is yet to be confirmed. The fecal–oral routes is a potential person-to-person transmission route as the virus has been found in fecal samples of affected patients.
The asymptomatic incubation period for individuals infected with 2019-nCov has been reported to be ~1–14 days. It has been estimated to be 5 to 6 days on average.
Although patients with symptomatic 2019-nCoV have been the main source of transmission, the virus can be spread from an asymptomatic person. This makes controlling its spread challenging, as it can be difficult to identify and quarantine individuals in time. Recovering patients have been reported to have transmit the virus.
How likely is someone to catch it?
How quickly this disease spreads between people is known as its transmission rate. The transmission of a disease is measured by something called a reproductive number (R0), which is the average number of people that are infected from an infectious person. The reproductive number for 2019-nCoV is estimated to be between 2-4. For comparison seasonal flu is about 1, so 2019-nCoV can spread more rapidly than seasonal flu. It is thought to spread faster than the two other coronaviruses- SARS and MERS.
The 2019-nCoV’s cell receptor is the human angiotensin-converting enzyme 2 (ACE2). The high affinity between ACE2 and 2019-nCoV S protein also suggested that the population with higher expression of ACE2 might be more susceptible to 2019-nCoV.
People in close contact with patients with symptomatic and asymptomatic 2019-nCoV, including health care workers and other patients in the hospital, are at higher risk of infection.
How do I know if I have caught it?
Symptoms of the patients who may have this include fever, cough, and myalgia or fatigue. The chest CT will demonstrate adnormal findings consistent with infection. Less common symptoms include sputum production, headaches, hemoptysis, and diarrhea.
Clinically, we should be alert of patients with an epidemiologic history and related symptoms.
What happens if someone catches it?
Most people who catch 2019-nCoV will recover fully. We don’t exactly know how many people will be seriously affected, but a suggested fatality rate (which is the cumulative deaths divided by cumulative cases) based on China data is between 0.39% and 4.05%. Based on more information from other affected countries, this is now thought to be between 3 and 4%. This fatality rate is lower than that of SARS (≈10%) and MERS (≈34%) and higher than that of seasonal influenza (0.01% to 0.17%). It is important to remember that this virus strain is new and medical professionals do not have a lot of data to be sure about this fatality rate for 2019-nCoV.
We do know that 2019-nCoV is more likely to affect older males. While it can affect all ages, adults are affected more than children. The risk to pregnant women is the same as to non-pregnant women. Patients with comorbidities such as heart disease, lung disease, diabetes and other medical problems are less likely to recover. Older people and those with co-morbidities are at greater risk, and mortality rates of up to 18% have been reported.
How is it treated?
So far, there has been no evidence from randomized controlled trials to recommend any specific treatment. Management is symptomatic, Clinical trials are underway to investigate interventions that are potentially more effective (e.g., lopinavir, remdesivir).
Why is the government cancelling large events and telling people to stay home? Is this just an over-reaction?
The Australian PM announced yesterday a ban on non-essential events of more than 500 people. In an outbreak, social distancing or staying home as much as possible helps slows spread of the virus. This is necessary because it flattens the curve. Our healthcare system has a capacity, and can only see so many patients at a time, with the added problem of health care professionals themselves getting sick too. If everyone gets sick at the same time, the healthcare system gets overwhelmed, and thus there will be a backlog of patients. While a majority of people will be fine regardless, the elderly, people with medical comordibites and those needing to be hospitalized, may not receive emergency care and our most vulnerable suffer. If we slow the spread of the virus over a longer period of time, the healthcare system will be less likely to have this backlog and patients can get the care that they need.
What can I do to protect myself?
As dental professionals and healthcare workers, the risk of cross infection is high between dental practitioners and patients. We see patients in close proximity and have risk of exposure to saliva, blood, and other body fluids, as well as handle sharp instruments. Dental professionals should be familiar with how 2019-nCoV is spread, how to identify patients with 2019-nCoV infection, and what protective measures should be adopted in order to help prevent transmission.
Firstly, identifying patients who may have the infection is imperative. In general, a symptomatic patient is not recommended to visit the dental clinic. If a patient has been to epidemic regions within the past 14 days, quarantine for at least 14 days is suggested. Consideration should be given to postpone non-emergency dental treatment.
Precheck triages to measure and recording the temperature of every staff and patient as a routine procedure may be implemented. A contact-free forehead thermometer is recommended. Patients should be asked about their health status and history of contact or travel. Higher risk countries include mainland China, Iran, Italy and South Korea. As at 15th March, all other countries are moderate risk.
Hand hygiene is the most critical measure for reducing the risk. SARS-CoV-2 can persist on surfaces for a few hours or up to several days, depending on the type of surface, the temperature, or the humidity of the environment. This reinforces the need for good hand hygiene and the importance of thorough disinfection of all surfaces within the dental clinic. Dental professionals should avoid touching their own eyes, mouth, and nose.
Measures to reduce transmission risk:
· The use of personal protective equipment, including masks, gloves, gowns, and goggles or face shields, is recommended
· Secondary protection should be considered for procedures with aerosol protection, where possible. This includes disposable doctor caps, protective goggles and face shield, working clothes with disposable isolation clothing or surgical clothes outside, and disposable latex gloves.
· Tertiary protection is necessary for patients with suspected or confirmed 2019-nCoV infection, and these patients should be treated in designated dental clinics.
· As respiratory droplets are the main route of transmission, particulate respirators (e.g., N-95 masks authenticated by the National Institute for Occupational Safety and Health or FFP2-standard masks set by the European Union) are recommended for routine dental practice.
· Aerosol-generating procedures or those that could induce coughing should be performed with caution.
Procedures at risk of inducing coughing or aerosols:
· Triplex syringe use
· Intraoral radiographs
· high- or low-speed drilling with water spray
· Ultrasonic scaling and cleaning
· Rubber dams, high-volume saliva ejectors and good ventilation can help minimize aerosol or spatter in dental procedures.
· High-speed dental handpieces should have anti-retraction valves
· The procedures may also be scheduled at the end of the day to prevent transmission.
· A preoperational antimicrobial mouthrinse is generally believed to reduce the number of oral microbes. Chlorhexidene may not be effective to kill 2019-nCoV. Since 2019-nCoV is vulnerable to oxidation, preprocedural mouthrinse containing oxidative agents such as 1% hydrogen peroxide or 0.2% povidone could be useful in cases, especially when rubber dam cannot be used.
· Effective and strict disinfection measures in clinic settings and public areas (such as the waiting room) are important. Appliances should also be frequently cleaned and disinfected, including door handles, chairs, and desks. If the building has an elevator, it should be disinfected regularly.
· The medical waste should be disposed in a timely manner.
· Dental procedures should be postponed at least 1 month for patients who have recovered from 2019-nCoV, based on SARS data.
References and Further Reading