COVID-19 is an infectious respiratory disease caused by the SARS-CoV-2 virus, belonging to the coronavirus family.
What causes the disease? SARS-CoV-2 virus (coronavirus).
How does infection occur?
mainly by droplets and airborne transmission – during talking, coughing, sneezing, singing,
by indirect contact – touching contaminated surfaces (door handles, handrails, telephones) and transferring the virus by hands to the mouth, nose, or eyes,
infection can occur approx. 1–2 days before symptoms appear and throughout the duration of the disease.
Who is the source of the virus? Patients with symptoms, people with a mild course, and asymptomatic carriers.
Incubation period Usually 2–14 days, most often approx. 5–6 days from contact with an infected person.
pregnant women (risk of more severe course, premature birth),
smokers,
unvaccinated people or long time after the last booster dose.
2. Symptoms of COVID-19
The course of COVID-19 can vary widely: from asymptomatic infection, through a mild cold, to severe pneumonia requiring hospitalization.
Most common symptoms
fever or low-grade fever,
cough (often dry),
sore throat,
shortness of breath / feeling of "lack of breath",
muscle and joint pain, headache,
general malaise, fatigue, weakness,
loss of smell and/or taste,
runny nose, stuffy nose, cold symptoms.
Symptoms are similar to flu or cold – without a test, it is not always possible to distinguish COVID-19 from other infections.
Course of the disease
In most people, the disease is mild or moderate and resolves within a few to several days.
Some patients experience complications or so-called "long COVID" – symptoms (e.g., fatigue, shortness of breath, concentration problems) can persist for more than 8 weeks.
In approx. a few percent of infected people, a severe form develops: pneumonia, respiratory failure, requiring oxygen therapy or mechanical ventilation.
Possible complications
pneumonia, lung fibrosis, and chronic respiratory failure,
damage to the heart muscle, heart rhythm disturbances, thromboembolic complications (embolism, thrombosis, stroke),
mental complications (anxiety, depression, memory and concentration disorders),
in children and young adults – rare but severe multisystem inflammatory syndrome (PIMS/MIS-C, MIS-A).
When is urgent medical consultation / ER necessary?
Immediately contact a doctor or call an ambulance if the following appear:
increasing shortness of breath, feeling of "lack of air",
pain or pressure in the chest,
bluing of lips, fingers,
high fever persisting for several days despite symptomatic treatment,
disturbances of consciousness, confusion, difficulty waking up,
symptoms of stroke (weakness of half of the body, drooping corner of the mouth, unintentional speech).
3. Where does COVID-19 occur?
COVID-19 is a global disease – it occurs on all continents and currently has an endemic character (circulates constantly in the population, with periodic waves of cases).
Countries and regions of highest risk
The risk of illness is present practically everywhere, but especially:
in countries with high population density and high mobility of residents,
in seasonal "waves" of cases (autumn/winter in the northern hemisphere),
in regions with a low percentage of vaccinated population.
Current recommendations and requirements of a given country are important for travelers (some countries may require: current vaccination, certificate of booster dose or test, especially for entry of elderly people or risk groups).
For whom is this information most important?
people traveling to countries with a weaker health care system,
people planning a longer stay abroad (studies, work, volunteering),
people from risk groups planning a trip during a period of increased morbidity – a booster vaccination is particularly important then.
4. How to protect yourself against COVID-19?
A. General prevention
These are actions you can use every day, in Poland and while traveling:
Hand hygiene
frequent hand washing with soap and water (minimum 20 seconds),
disinfection with alcohol-based agents (60–80%),
avoiding touching the face (eyes, nose, mouth) with dirty hands.
Safe environment
if possible, keeping distance from people with symptoms of infection (cough, runny nose, fever),
airing rooms, especially with a larger number of people,
limiting stay in cramped, poorly ventilated places.
Protective masks
recommended especially:
during periods of increased cases,
in public transport,
in people from risk groups,
in contact with sick people or with reduced immunity.
Taking care of immunity
adequate amount of sleep,
balanced diet,
physical activity,
avoiding smoking.
General prevention does not replace vaccination but complements it very well.
B. Vaccination against COVID-19
This is the most effective method of protection against severe course, hospitalization, and death due to COVID-19.
Types of vaccines
Currently used mainly:
mRNA vaccines – contain genetic information based on which the body produces viral protein and learns to recognize it,
protein vaccines – contain ready-made viral protein (antigen) against which the body produces antibodies.
These are preparations not containing live virus – they cannot cause COVID-19.
people working with many people (health care, education, trade, transport),
travelers – especially during periods of increased cases or going for longer.
Current preparations are adapted to the latest virus variants (e.g., JN.1), which increases the effectiveness of protection.
Vaccination schedule
The detailed schedule depends on:
age of the patient,
previous doses of earlier preparations,
current recommendations of Ministry of Health / sanitary inspection / WHO.
Most often, a booster dose is used in the form of a single intramuscular injection (arm). In some age groups or special situations, a 2-dose schedule may be recommended.
In practice:
it is recommended to take another booster dose once per autumn-winter season, especially in risk groups,
in people who have not been vaccinated before or took the last dose a very long time ago, the doctor may propose a "primary + booster" schedule.
Booster doses and duration of immunity
Immunity after vaccination and/or illness weakens over time, especially against new virus variants.
Booster doses:
strengthen and "refresh" immunity,
better protect against severe course, hospitalization, and death,
are particularly important for the elderly and chronically ill.
Additional notes
An absolute contraindication to vaccination is a severe allergic reaction (anaphylaxis) after the previous dose or to a vaccine component (e.g., PEG, polysorbate 80).
Temporary contraindications (vaccination is postponed):
high fever,
acute infection,
exacerbation of chronic disease.
No vaccine gives 100% protection against infection, but significantly reduces the risk of severe course, hospitalization, complications, and death.
5. Summary
COVID-19 is a disease that may look like a common cold, but in some people leads to severe pneumonia, respiratory failure, and dangerous organ complications.
It is worth getting vaccinated because:
vaccination definitely reduces the risk of severe course, hospitalization, and death,
protects people from risk groups (seniors, chronically ill, pregnant women),
helps limit virus transmission in family, work, during travel.
Who should especially consider vaccination / booster dose?
people 65+,
people with chronic diseases,
people with reduced immunity,
pregnant women,
smokers,
people planning a trip abroad, especially in the autumn-winter season or to regions with a larger number of cases.
When is the best time to get vaccinated before travel?
Optimally at least 2 weeks before departure so that the body has time to develop a protective immune response.
If you are planning a trip or belong to a risk group – it is worth reporting to a pharmacy vaccination point well in advance to select the best preparation and vaccination schedule.