There is an intimate association between people’s sleep health and their immune health. In fact, those who takes less than 7 hours sleep are three times more likely to become infected by rhinovirus known as the common cold. Also, when people get a flu shot, individuals who do not take enough sleep went on to produce less than 50% of the normal antibody response compared to those who take enough sleep.

Does it sound natural?

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There is an intimate association between an individual's sleep and their immune system. Those who have had less than the recommended seven hours of sleep are three times more likely to become infected with rhinovirus, commonly referred to as the common cold. After been given flu shots, individuals who slept less than recommend went on to produce less than 50% of the normal antibody response compared to those who had.

I assume this is for an essay. One important thing, you don't "take sleep" sleep is more verb than a noun so it's something you do "to sleep" "have slept" "are/is sleeping"

I think it's best not to use phrases like "Infact" and "also" to start sentences and use them after commas instead.

Also this only really applies for writing but if a number is under 10 you want to spell it out, so "seven" instead of "7".