When to get a flu shot and how long does protection last: at the beginning of the epidemic season, a doctor answered key questions
Kyiv • UNN
Family doctor Viktoriia Dmytruk said that it is best to get vaccinated against the flu in the fall, as soon as the drugs appear in medical facilities. Immunity is formed within a few weeks and reliably protects throughout the entire season, while natural immunity after illness is much narrower.
It is best to get vaccinated against the flu in the fall, as soon as the preparations appear in medical institutions. Immunity is formed within a few weeks and reliably protects throughout the season, while natural immunity after illness is much narrower. Viktoria Dmytruk, a family doctor at the Odrex Family Polyclinic, told UNN correspondent about this.
Details
Flu is not a common cold. The disease begins suddenly and acutely: a sharp increase in temperature occurs in the first hours, and a cough, stuffy nose, sore throat, and difficulty breathing appear a little later. The danger of the flu lies not only in its severe course but also in possible complications that can affect the heart, lungs, or kidneys.
When is the best time to get a flu shot?
According to Dmytruk, in Ukraine, flu vaccine supplies traditionally begin in the fall – it is during this period that medical institutions receive the first batches of preparations.
Flu vaccines usually arrive in Ukraine in the fall. It is worth getting vaccinated as soon as the vaccine becomes available at your hospital. This will allow time (approximately 1–3 weeks) for immunity to form before the virus begins to spread in the country.
How long does immunity last after vaccination?
Immunity after a flu shot lasts for a certain period. The highest level of antibodies is formed a few weeks after vaccination and lasts for an average of six to twelve months. That is why doctors recommend getting vaccinated every year – so that the body is ready to meet a new virus at any time.
It should also be taken into account that the flu virus is constantly changing. Even if a certain number of antibodies remain in the blood longer, their effectiveness against new strains decreases.
The antibody level gradually decreases over 6–12 months. In addition, the virus can mutate, so the most effective protection is 3 weeks after vaccination for 6 months.
When asked whether a vaccine given at the beginning of the year, in January or February, would be effective during the new epidemiological season, the doctor advised renewing the vaccination.
"Such a vaccination is still useful, because you can get the flu in March-May. But for the next season, a new vaccine is needed, because the virus is constantly mutating. That is why new vaccines are created every year, the name of which indicates the corresponding years, for example: "Vaxigrip Tetra 2025/2026," Dmytruk says.
How does a flu vaccine differ from natural immunity after vaccination?
Natural immunity after having the flu is usually formed only against the specific strain of the virus that the person had, says Dmytruk. If a different type of flu circulates in the next season, the existing protection may be insufficient. Instead, the vaccine contains several of the most likely strains predicted by the WHO and provides broader and more predictable protection.
After an illness, the body "remembers" only the strain you had. The vaccine, however, provides broader and more predictable protection.
She added that all vaccines available in Ukraine are inactivated – that is, they contain only virus particles that are not capable of causing illness. Thanks to this, the immune system "gets acquainted" with the virus and learns to quickly recognize it. When the real virus enters the body, the defense is already ready and begins to act immediately.
"That is why in vaccinated people, the flu usually passes more easily and quickly, because the body does not need to spend time "studying the enemy," says the doctor.
Addition
On September 29, 2025, the epidemic season of influenza, COVID-19, and other acute respiratory viral infections (ARVI) began in Ukraine. It will last until May 17, 2026.
On September 23, the Ministry of Health announced that "the first 76,000 doses of flu vaccine will soon go on sale."
Doctors added that a batch of Korean-made vaccine has already passed state quality control and will soon be available for sale in pharmacies and medical institutions. More than 100,000 doses of French vaccine are also being checked, after which they will also go on sale.
All vaccines in Ukraine undergo mandatory laboratory control, and only after a positive conclusion from the State Service of Ukraine for Medicines and Drug Control can they be used for vaccinations.
Recall
Earlier, UNN wrote that Deputy Minister of Health Ihor Kuzin predicts an increase in COVID-19 incidence in late September – early October. At the same time, restrictive measures and lockdown are unlikely, as the indicators are significantly lower than last year.