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Left or right? In which arm should vaccines be injected?


Left or right?

In which arm should vaccines be injected?

Researchers have studied various ways in which vaccines

(since their emergence nearly two centuries ago)

affect the body's immune system to launch a complete attack on pathogens.

But an important question that has been the concern of health experts

around the world so far is: In which arm should vaccines be injected.

In this regard :

Marcel Kerlin, a specialist in infectious diseases from the University of

Oregon Health and Science (OHSU)


"This issue was not extensively studied, so we decided to check it."

After analysing the scientific literature on this subject

the research team found only 4 research papers, and the results were mixed.

One trial found that influenza vaccines administered to children aged 2, 3

and 4 months in different arms resulted in higher levels of

antibodies than when administered in the arm itself.

In the recent study, researchers at OHSU tested the antibody levels of

947 participants who received two doses of the "COVID-19" vaccine.

Half of the participants received

the second dose of the vaccine in the same arm, while the other half received

additional doses in the other arm. Four weeks after the second dose

SARS-CoV-2 antibodies were 1.4 times higher in those

who received the vaccine in the other arm.

The Kerlin team explained that

when administering the vaccine in the muscle, immune cells recognize

the antigens in the drug, and transfer them to the lymph nodes

for further immune response, leading to the preparation of

the immune system against this antigen by sending the required signals.

Different aspects of

the body are associated with different lymph nodes, therefore

the body may be more cautious by stimulating the immune 

response on both sides (arms).

"By switching arms, memory is formed in 

two locations instead of one," explains Kerlin.

Just three weeks later

OHSU researchers noted that vaccination in both arms began to

show better results, and these benefits gradually improved

peaking in the fourth week and lasting for several months thereafter.

The study was published in the Journal of Clinical Investigations.

Detection of a negative impact on

sleep for mild COVID-19

COVID-19 is known to :

cause a dry cough and deprive you of your sense of taste and smell. 

But a team of researchers now say it may leave you with insomnia at night as well.

  • who during their illness did not sufficiently
  • experience symptoms to be hospitalized.

Participants were over the age of 18, diagnosed with "COVID-19" six months

before the questionnaire, and reported no history of

insomnia or psychiatric conditions.

76.1% of participants reported insomnia

and 22.8% :

reported severe insomnia. Half of participants said they woke up more at night

while one third said they found it difficult to sleep

slept worse, slept less and struggled to sleep.

Dr. Huang said that while previous studies had looked at insomnia and "Covid-19"

patients in hospitals, none had looked at the impact on 

sleep in those with mild infections.

The team claimed that :

compared to these studies, patients with minor infections were more likely to

 report insomnia than the general population

and patients with "COVID-19" in hospital.

This may be because patients recovering from COVID-19 become

more stressed and sensitive to changes in their physical health

leading them to consider their sleep worse.

However, more studies are needed looking at the relationship

between COVID infection and mental health problems and insomnia.

Dr Huang noted: 

"If insomnia doesn't bother you too much, you can take some simple measures

such as taking a warm bath before bed, turning off 

your phone at least one hour before going to bed

exercising for 30 minutes a day, and avoiding caffeine after 4 pm."