COVID-19

Cúm là gì?

COVID-19 disease is caused by infection with the SARS-CoV-2 virus of which there are many different strains and subvariants.  In 2024, the Omicron variant is the predominant strain circulating globally. 

Since its emergence in 2019, COVID-19 disease has had vast impacts on society. In addition to the public health implications, the economic, social and mental health effects have been and continue to be significant.   

Bạn cần tìm gì?

Infections can be asymptomatic or can result in a spectrum of symptoms, from mild respiratory symptoms to more serious disease affecting multiple organs and systems. Severe disease can lead to hospitalisation, mechanical ventilation, and can be fatal.    

Common symptoms of acute infection can include rhinorrhoea (runny nose), sneezing, headache, sore throat and fatigue. The symptoms of fever, loss of smell or taste and persisting cough seen in infections with previous variants (Alpha, Beta, Gamma, Delta) are less likely to occur in infections with the Omicron variant. 

Long COVID is a chronic condition that can occur following acute infection. It is the persistence of symptoms for greater than 3 months after an initial infection that cannot be attributed to other causes. Long COVID can have a huge impact on an individual’s quality of life, mental health and ability to participate in work or schooling. Long COVID is more common in people who have experienced severe COVID-19 disease, those who had underlying medical conditions prior to infection (e.g. hypertension, chronic lung disease, diabetes, obesity) and those who are unvaccinated.  

Paediatric Multisystem Inflammatory Syndrome Temporally associated with SARS-CoV-2 (PIMS-TS), or Multisystem Inflammatory Syndrome in Children associated with COVID-19 (MIS-C), is a newly described condition that has been reported in children in the first 2-6 weeks after COVID-19 infection. It is an inflammatory condition, similar to bệnh Kawasakivà được đặc trưng bởi phát ban, sốt, sốc và đau bụng. Trẻ em bị PIMS-TS hầu như luôn phải nhập viện để điều trị.

Bệnh lây truyền qua đường nào

COVID-19 is transmitted through the inhalation of virus particles made airborne when an infected person coughs, sneezes, breathes, speaks or sings. Droplets containing virus particles can contaminate surfaces and can be spread when a person touches these surfaces and then touches their nose, mouth or eyes. Poorly ventilated settings can also contribute to the spread of COVID-19 because aerosol particles can remain suspended in the air for several hours longer than in well-ventilated settings. 

The incubation period for the disease is 1 to 14 days, with most individuals displaying symptoms 3 days after being exposed. Individuals are most infectious in the 2 days before their symptoms begin and the early stages of their illness. People with asymptomatic disease can still infect others.   

Dịch tễ học

Kể từ năm 2019, hơn 774 million infections have been reported worldwide contributing to more than 7 million deaths. True figures are likely to be much higher. Serosurveys indicate that by December 2022 more than two thirds of adult Australians had been infected with SARS-CoV-2.

Individuals with immunocompromise, advancing age (particularly > 70 years), obesity, respiratory conditions, heart disease, diabetes, renal disease, liver disease, neurological conditions and disability are more likely to experience severe symptoms if infected with SARS-CoV-2. Pregnancy in unvaccinated people is also recognised as a risk factor for developing severe disease; however, this risk has declined substantially since the Omicron variant became the predominant circulating strain. 

Certain occupations, such as working in healthcare, increase likelihood of exposure to SARS-CoV-2 and therefore infection.   

Phòng ngừa

Strategies to reduce risk of transmission of COVID-19 disease include standard precautions such as hand hygiene, wearing masks when remaining socially distant is not possible and ensuring indoor spaces have good ventilation.   

While natural infection does provide some immunity, it is not lifelong, and the emergence of newer strains contributes to repeat infections. 

Vaccination aims to reduce the severity of COVID-19 symptoms and the need for hospitalisation. There are 2 vaccine brands available for use within Australia:  

• Comirnaty (Pfizer) vaccine containing nucleoside-modified mRNA encoding the spike glycoprotein of SARS-CoV-2   
• Spikevax (Moderna) vaccine containing nucleoside-modified mRNA encoding the spike glycoprotein of SARS-CoV-2   

As newer variants of các SARS-CoV-2 virus emerge, vaccines are updated ĐẾN target the strains that are circulating; where possible, these should be used preferentially. 

Table 1: Vaccine brands and type available for use by age group

các ô được tô bóng cho biết rằng vắc-xin không có sẵn để sử dụng cho nhóm tuổi này.
shaded boxes indicate preferred vaccines in this age group.
✓ may be used in this age group.
* Comirnaty (Pfizer) Omicron XBB.1.5 is registered for use in individuals aged 6 months to 4 years and supply is anticipated in early 2024. When stock of this formulation becomes available this vaccine will be preferentially recommended in this age group over the Original [Maroon cap] vaccine.

khóa học chính

Immunocompetent people aged 5 years and over require a single dose of vaccine to complete their primary course.

People aged 6 months and over with suy giảm miễn dịch nặng, and children aged 6 months to 4 years with increased risk of severe disease, require 2 liều, 8 weeks apart. A 3rd dose may be considered based on individual circumstances.

Further doses

Following receipt of a primary course, recommendations for further doses vary depending on the age of the individual and their risk factors for severe disease.  

Table 2: 2024 recommendations for COVID-19 booster doses (adapted from ATAGI statement on the administration of COVID-19 vaccines in 2024)

các ô được tô bóng cho biết rằng vắc-xin không có sẵn để sử dụng cho nhóm tuổi này.

Tác dụng phụ sau khi chích vắc-xin

Tác dụng phụ thường gặp 

Most side effects following COVID-19 vaccination are mild and can include đau tại chỗ tiêm, fatigue, headache, lymphadenopathy and fever. 

Tác dụng phụ hiếm gặp  

Viêm cơ tim (viêm cơ tim) và viêm màng ngoài tim (viêm màng bao quanh tim) are rare conditions that have been reported following administration of COVID-19 vaccines. They are most commonly associated with viral infections (including COVID-19 disease) but can also be triggered by other factors such as medications and autoimmune conditions. In the setting of vaccination, the peak risk group for myocarditis is young adult males aged between 16 and 24 years following a second dose of vaccination. Pericarditis occurring after vaccination is more common in the 20 to 45 year old age group for both males and females. 

Huyết khối với giảm tiểu cầu (TTS) là một tình trạng hiếm gặp đã được báo cáo xảy ra ở những người trước đó đã tiêm vắc-xin COVID-19 Vaxzevria (AstraZeneca). Since March 2023, Vaxzevria is no longer available for use in Australia.

Các câu hỏi thường gặp

Tài liệu

• MVEC: Nền tảng vắc-xin 
• MVEC: Thuốc ức chế miễn dịch và vắc-xin
• Báo cáo an toàn vắc-xin COVID-19 của Victoria
• Hướng dẫn lâm sàng của ATAGI về các lỗi tiêm vắc xin COVID-19
• Bộ Y tế và Chăm sóc Người cao tuổi của Chính phủ Úc: Vắc xin COVID-19 quốc tế được Úc công nhận
• Australian Immunisation Handbook: COVID-19
• CDC: COVID kéo dài hoặc tình trạng sau COVID