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Have you been vaccinated against the seasonal flu?

Influenza (Seasonal flu) is a contagious respiratory illness caused by influenza viruses. It can occur throughout the year but it usually peaks during the winter. It is caused by four types of viruses: A,B ,C and D. Influenza A viruses are further subdivided into sub-types according to the combination of two proteins present in the virus: hemagglutinin (HA) and neuraminidsase (NA). Example, the A(H1N1)pdm09 (the virus responsible for the 2009  pandemic) and A(H3N2). Only influenza type A viruses have the potential to cause pandemic. Influenza B viruses are not classified into sub-types are broken into lineages. Currently, there are two influenza B viruses; B/Yamagata and B/Victoria lineage. Influenza C is rarely reported as a cause of human illness. Influenza D virus only affects cattle and so far is not known to cause any illness on humans. All age groups are at risk for infection but children below the age of 5, adults aged 65 or over, pregnant women and those with health conditions are at in increased risk for contracting the flu. The influenza viruses can easily spread from the one individual to the next through sneezing or coughing, since these viruses are present in droplets of saliva and mucus. It can also live for a short time on things from phones , doorknobs etc. and therefore one might breathe in the virus by touching surfaces infected with influenza viruses. The time from infection with the virus to illness, also referred to as the incubation period, is about 2 days.

 The symptoms of the flu are:

  • Fever
  • Dry cough
  • Runny or stuffy nose
  • Fatigue
  • Nausea, vomiting and diarrhea in some people.
  • Headache
  • Sore throat
  • Sore muscles and joints

The best way to prevent the season flu is by taking the seasonal flu vaccine. It can be administered by injection or nasal spray depending on the country. The injection contains different inactivated forms of the virus which upon entry into body triggers an immune response. Your body produces antibodies and T-lymphocytes in response to the virus. The ‘memory’ T-lymphocytes will remember the structure of inactivated forms of the virus supplied through the vaccine. This is extremely helpful as when the activated form of the virus manages to get into the body, your body would already be prepared for it and produces antibodies against it much faster.

Apart from seasonal flu vaccine one must take precautions by:

  • Regularly wash hands
  • Avoiding close contact with infected people
  • Good respiratory hygiene- Making sure to use tissues after sneezing or coughing and making sure they are disposed of after use.
  • If feeling unwell or someone you know is unwell, isolate immediately.

The influenza season started  on week  48 of 2017. So far, influenza A(H3N2) and B/Yamagata viruses constituted the majority of influenza detections.  The other least detected being the influenza A(H1N1 aka swine flu) and B Victoria lineage. Both the national influenza centres and national influenza laboratories from 106 countries reported that around 62.4% of influenza viruses detected was influenza A while 37.6% was influenza B.

In Europe, in week 48 around 11 EU/EEA countries reported 10% or more positive sentinel specimens positive for the influenza virus. The European Centre for Disease Prevention and Control (ECDC) reported that the first detections indicated the circulation of A(H3N2) and B/Yamagata virus. Until week 49, influenza B/Yamagata virus seemed to predominate in the region. Vaccine effectiveness against this virus is expected to be low since it is not included in the trivalent vaccine but against A(H1N1) it is expected to be high.

In North America, influenza activity increased and influenza- associated hospitalizations were higher then normal in week 49 indicating an early season according to World Health Organization (WHO). The Centers for Disease Control and Prevention (CDC) reported a sharp increase in positive cases with 14% of respiratory specimen submitted being positive for the influenza virus during week 50. Public health laboratories in the US reported that the influenza A virus accounted for 86.7% of all influenza detections, while clinical laboratories reported a similar percentage of 85%  during the same week. The majority of the influenza A viruses is H3N2 (88.7%). Influenza A(H1N1)pdm09 was present in only 8.4% of the positive cases. Influenza A (H3N2) seems to be predominating in Canada and Mexico.

In Tropical countries of central America, Carribbean and South America, influenza activity varied. In Central American and Caribbean countries, influenza activity remain low but the respiratory syncytial virus (RSV) remained high, especially in Panama. In El Salvador and Costa Rica, influenza activity is persisting. In Brazil, RSV levels and influenza activity decreased.

In Western Asia, influenza activity increased with influenza A(H1N1) predominating.

In Central Asia, low to no influenza was detected.

In East Asia, influenza activity in general remained low with the exception of China, where influenza activity is increasing. The influenza B/ Yamagata lineage is predominating followed by influenza A(H3N2).

In Tropical Asia, low levels of influenza activity was detected.

In the African region, influenza virus was detected in Ghana, Burkina Faso and Sierra Leone with influenza A(H1N1)pdm09 virus predominating. In Middle Africa, there are occasional detections of influenza A virus in Cameroon, while in East Africa, influenza A(H3N2) and influenza B virus were reported.

In Oceania, influenza activity was reported to be at inter-seasonal levels. In Australia, the number of specimen positive for the influenza has sky-rocketed in the past week, with the number of cases being more then double of last year’s total.

Credits to European Centre for Disease Prevention and Control (ECDC), Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO).


  1. Thanks for stopping by my blog and liking my post on heart function linked to brain’s memory center. I am enjoying my visit to yours. I agree with you on the need for a flu shot, but have found that people have very strong feelings about this, on both sides. Good luck with your blogging!

    Liked by 1 person

    • Thanks! Well, this year vaccines are not effective as they thought they would be due to a mutant strain, something which is happening in the US, giving rise to more positive cases. Still, i believe getting vaccinated is a must, since it will protect you if you have the other influenza viruses as discussed in the article 🙂


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