COVID-19

Overview

COVID-19 is a respiratory disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

In December 2019, a cluster of pneumonia cases was detected in Wuhan, China. The pathogen involved was identified as a novel coronavirus (SARS-CoV-2), and the disease was named COVID-19. The World Health Organization (WHO) declared the COVID-19 outbreak a Public Health Emergency of International Concern (PHEIC) from 30 January 2020 to 5 May 2023.

Disease epidemiology

In Singapore, the first case of COVID-19 was confirmed on 23 January 2020. Like other countries, Singapore has experienced multiple waves of infection (i.e. Alpha, Delta, and Omicron) since the start of the pandemic.

Pathogen

SARS-CoV-2

Transmission

COVID-19 primarily transmits through inhalation or direct deposition of infectious respiratory particles (IRPs) from coughs, sneezes or speech. It can also spread via contact transmission when IRPs settle on surfaces or transfer through contact (e.g. handshake) before reaching the mouth, nose or eyes.

Incubation period: Varies across variants from 0 to 14 days, with more recent variants such as Omicron having a shorter range from 0 to 8 days.

Infectious period: From 2 days before the onset of symptoms until 7 days after onset. The infectious period is affected by factors such as immune system, disease severity, and prior infections.

Clinical features

The signs and symptoms of a COVID-19 infection range from mild respiratory symptoms to severe illnesses such as pneumonia.

Infection is mild in the majority of people, and up to 1 in 3 infected persons are asymptomatic.

Common symptoms of COVID-19 include:

• Fever and chills

• Sore throat

• Cough

• Nasal congestion, rhinorrhoea

• Headache

• Anosmia

• Ageusia

• Fatigue

• Myalgia

• Nausea

• Diarrhoea

In severe cases, COVID-19 can manifest as pneumonia with shortness of breath and chest pain.

Severe complications include:

• Respiratory failure

• Acute Respiratory Distress Syndrome (ARDS)

• Thromboembolism

• Cardiovascular complications

• Encephalopathy

• Inflammatory complications (e.g. Multisystem Inflammatory Syndrome)

“Long COVID” or Post-Acute Sequelae of COVID-19 (PASC)

"Long COVID" or PASC is a general reference to new or persistent symptoms experienced by some persons 4 weeks or more after a COVID-19 infection with no alternate diagnosis.

Such persistent symptoms are more commonly seen after severe COVID-19 and among unvaccinated persons. Most symptoms, such as cough and fatigue, resolve on their own over time. However, persons with more severe symptoms, such as shortness of breath or chest pain, may require further medical assessment and care, and are advised to seek medical attention. There is no single response to address these persistent symptoms and treating physicians would be best placed to assess and advise patients on their management and recovery, and on the resumption of daily activities. As necessary, these persons will be referred for further care and support services based on their condition and medical needs.

Risk factors

Individuals at greater risk of severe disease or complications when infected include:

• Seniors aged 60 years and above

• Pregnant women

• Persons who are immunocompromised or have concurrent medical conditions such as obesity, diabetes, heart, or lung disease

Diagnosis

Detection of COVID-19 virus in respiratory samples through rapid SARS-CoV-2 diagnostic tests (antigen-based) or polymerase chain reaction (PCR).

Treatment and management

COVID-19 is usually mild and self-limiting. Supportive care and symptomatic treatment, such as treatment with antipyretics, plenty of fluids, and adequate bed rest are usually sufficient in the management of acute symptoms of COVID-19.

Oral antivirals and immunomodulatory agents may be prescribed for patients at high-risk of severe COVID-19.

For patients who develop severe illness (i.e. requiring oxygen supplementation), SARS-CoV-2-specific therapies can be beneficial.

Precaution, prevention and control

Prevention and control strategies for SARS-CoV-2 focus on reducing transmission of infectious respiratory particles (IRPs) through appropriate respiratory protection, good ventilation, and environmental hygiene.

Patients with suspected or confirmed COVID-19 should wear a surgical mask and be isolated when feasible. Good hand hygiene and respiratory etiquette should continue to be reinforced for both healthcare workers and the public.

Contact management

No specific management of contacts is required.

Vaccination

COVID-19 vaccination protects against severe disease, such as hospitalisation and deaths.

* From 24 January to 30 April 2025, the updated JN.1 Novavax/Nuvaxovid COVID-19 vaccine will be available at selected Healthier SG General Practitioner (GP) clinics under the NVP. As this JN.1 vaccine formulation will no longer be supplied by the manufacturer once the current stocks expire, eligible individuals who wish to receive the updated JN.1 Novavax/Nuvaxovid vaccine will have to do so by 30 April 2025.

The following applies to unvaccinated individuals who are receiving COVID-19 vaccination in 2024/2025:

1. Ages 6 months to 4 years: 2 vaccine doses, 8 weeks apart

2. Ages 5 years and older: 1 vaccine dose

Vaccinated individuals aged 6 months and above who are receiving an additional dose of COVID-19 vaccination in 2024/2025, should receive it at an interval of around 1 year (and at least 5 months) from the last vaccine dose.

Vaccination is free under the NVP for all Singapore Citizens, Permanent Residents, Long Term Pass Holders and certain Short Term Pass holders.

Notification

COVID-19 is not a legally notifiable disease in Singapore.

Note: While single cases are not notifiable, medical practitioners should report events of public health significance (e.g. cluster of infectious diseases in the community). Please refer to the Infectious Disease Notification for more information.

Resources

Please refer to the Weekly Infectious Diseases Bulletin for the latest COVID-19 statistics in Singapore.

For more information on COVID-19, please refer to the WHO website.

Click here for the latest WHO update on the COVID-19 situation.

Click here for more information on national COVID-19 vaccine recommendations.

For general travel advisory, please refer to Health Advice for Travellers.