Summary from elsewhere
The International Space Station (|SS) has low microbial diversity, which could lead to astronaut health issues, according to a study published in Cell.
Researchers found that the microbial communities resemble those found in sanitized environments like hospitals rather than natural settings.
Co-senior study author Pieter Dorrestein explains that increasing microbial exposure could improve astronaut health during long-term space travel.
The study suggests incorporating natural elements, like soil, into the ISS to enhance microbial diversity and astronaut well-being.
The study in question:
To be honest: I don’t think that’s much of a problem (unless…). The pathogens on earth are all adapted to attack (if you want to use this verb on a cellular level) us and others on earth. They would most likely not pose a threat to any other lifeforms that have evolved on other planets, unless our way of evolution is the only one which is able to produce life. And that is a big unless, because apart from the panspermia theory (life came to us with a meteor) there is no reason to assume that life has to work the same way it does for us.
Time travel interactions however, those could be a problem
The main issue to conquer once we are able to go back, is how to go back without dieing or killing off a significant fraction of our ancestors, creating temporal paradox.